The Open University

Professional biography

Presently, I am Senior Research Fellow at the Centre for Electronic Imaging (CEI). Most of my work is focused on the design and evaluation of novel image sensors for scientific applications, manufactured in CMOS technology. The research topics I am working on now are high dynamic range CMOS imagers, fully depleted CMOS sensors for maximum quantum efficiency, ultra-low noise, CCD-in-CMOS devices and radiation damage effects.

From 2001-2008 I worked at STFC Rutherford Appleton Laboratory (RAL) on the development of 3 generations of column-parallel CCDs and 2 generations of CMOS-based in-situ storage image sensors, readout ASICs and support electronics for the vertex detector at the proposed International Linear Collider. I also lead the development of one of the first devices in the world incorporating buried channel CCD in specially modified 0.18 μm CMOS process.

From 2008-2012 I was with the technology consultancy company Sentec Ltd. in Cambridge (UK), working on a variety of new technologies for industrial and consumer applications.

Qualifications

MSc in Applied Physics from Sofia University, Bulgaria (1994).

PhD in Physics from Saga University, Japan (2001).

Research interests

My research interests are in semiconductor image sensors for science, where the term "imaging" covers everything from infrared, visible and X-ray wavelengths to minimum ionising particles in high energy physics.

CMOS image sensors
Infrared image sensors
CCD-in-CMOS devices
High performance CCDs
Semiconductor physics
Device simulations
Radiation damage effects in semiconductors and their influence on device performance
Detector electronics and data acquisition systems

Teaching interests

Impact and engagement

External collaborations

International links

Research groups

Name	Type	Parent Unit
e2v Centre for Electronic Imaging	Centre	Faculty of Science

Externally funded projects

Infrared image sensors for space and Solar System exploration

Role	Start date	End date	Funding source
Lead	01 Feb 2023	31 Jan 2027	STFC Science & Technology Facilities Council
Industrial CASE studentship on infrared sensors for space imaging.

JANUS - Signal dependent baseline suppression investigation

Role	Start date	End date	Funding source
Lead	01 Mar 2022	31 Mar 2022	UKSA UK Space Agency
The OU was a member of the full “core team” within JANUS responsible for the CIS115 detector development and test programme, but the OU JANUS grant expired on 31 March 2021. Analysis of the Flight Model JANUS instrument calibration data has recently identified a problem with a variable detector baseline. OU propose to characterise the effect for the CIS115 to support efforts to calibrate this out on PFM JANUS. OU Project outcomes will be characterisation of effect and suggested ground correction method(s). This would allow the JANUS PI and JANUS science team to implement any corrections needed for the mission operations.

TreeView Phase 2

Role	Start date	End date	Funding source
Co-investigator	01 Oct 2021	31 Mar 2022	UKSA UK Space Agency
TreeView is an Earth Observation mission that will achieve precision forestry from space in the support of Nature-Based Solutions to tackle climate change. The expansion of tree cover is a critical component of the path to net zero but reaching this target will require extensive management of this resource. Through leveraging next-generation optical sensor technology and innovations across the payload and spacecraft development, TreeView will provide multispectral data at a ground sampling resolution on the scale of individual trees, providing measurement and monitoring capabilities at an unprecedented level. The proposed project builds on the successfully concluded feasibility study and will progress the hardware and software elements of TreeView to a Preliminary Design Review (PDR). The activities will focus on the development of the instrument from an initial concept to a finished design. The satellite bus is being developed and qualified through a European Space Agency funded project and has already passed its PDR. A mission specific “delta” PDR will be held in future phases of the TreeView programme once the payload PDR’s have also been passed to confirm the complete satellite is at sufficient design maturity. The data processing pipeline embodied largely in the Ground Segment, and outputting data products for dissemination, raw data for archiving and utilising ground validation will be reviewed in a Ground Segment PDR. Subject to further funding, the outcome of this project and a successful PDR will enable the TreeView team to commence procurement to develop the Engineering Model of the instrument and payload for the TreeView mission. In parallel spacecraft procurement and development of the Ground Segment through a model of commercially purchased services, national facilities, and support from the science team could commence. TreeView is on track to develop and launch the satellite and return data by the end of the Financial Year 2024-25.

[Te2v] CIS123 BSI Characterisation

Role	Start date	End date	Funding source
Lead	01 Sep 2021	31 Mar 2023	e2v Teledyne e2v
Characterisation of CIS123 TDI CMOS image sensor in backside illuminated (BSI) variant.

Nano-Black Coating on Silicon CMOS Image Sensors for Extreme Sensitivity

Role	Start date	End date	Funding source
Co-investigator	01 Apr 2021	31 Dec 2022	ESA (European Space Agency)
We propose to manufacture CMOS image sensors with a novel nanostructured black silicon (b-Si) anti-reflection (AR) coating and to characterize their electro-optical performance. Initial results from tests of this coating, developed by Aalto University (Finland), show that it can increase the quantum efficiency (QE) of silicon detectors to nearly 100% throughout the visible and NIR wavelengths, and even exceed 100% QE below 300 nm. For CMOS image sensors the nearly flat QE would be a breakthrough development, considering that traditional AR coatings are optimised only for a specific wavelength band. The study is needed to establish whether the b-Si process, presently used only on large area p+/n photodiodes, can be applied to established commercial backside-illuminated (BSI) CMOS image sensors using p-type epitaxial substrate, manufactured by our industrial partner Teledyne e2v. We plan to characterise the QE over the wavelength range 400-1000 nm and to establish whether the b-Si coating deteriorates the uniformity of the photoresponse and the dark current of the sensors. If successful, this project will represent a major advance in AR technology for pixelated sensors and would substantially improve the performance of future silicon detectors for space and other applications.

A universal model for detector simulations for space applications

Role	Start date	End date	Funding source
Co-investigator	01 Feb 2021	31 Jan 2025	ESA (European Space Agency)
ESA, in partnership with ESO, is developing a general detector simulation framework called Pyxel, to be able to share a single well-understood framework among many projects and missions. Due to the advanced research into detector physics and simulation being done at the CEI, ESA has agreed to co-fund a PhD studentship to do more research of the physics and fundamental understanding of the detectors for a variety of applications and using this new knowledge to develop exciting new capabilities for Pyxel linking it with the CEI involvement in space missions such as Euclid, SMILE, JUICE, and Gaia.

Radiation characterisation of infrared detectors for future Mars exploration

Role	Start date	End date	Funding source
Co-investigator	19 Jan 2021	31 Mar 2022	UKSA UK Space Agency
Development of IR detectors for use in future Mars exploration imagin insturments.

[Te2v] CIS123 7µm

Role	Start date	End date	Funding source
Lead	01 Nov 2020	31 Oct 2021	e2v Teledyne e2v
Simulation of a variant of the CIS123 TDI CMOS image sensor with 7 µm pixel pitch.

ESA NPI Gaia radiation damage

Role	Start date	End date	Funding source
Co-investigator	01 Sep 2020	31 Aug 2023	ESA (European Space Agency)
European Space Agency (ESA) Network Partnering Initiative (NPI) funding to support PhD student Saad Ahmed, who is working on radiation damage of the Gaia focal plane detectors. This funding will allow Saad to work more closely with ESA using in-orbit calibration data from the Gaia space telescope, and to get access to test equipment located at the ESA Research and Technology Centre (ESTEC) in Holland.

[Te2v] CIS123 Rev.E

Role	Start date	End date	Funding source
Lead	01 Jun 2020	31 May 2021	e2v Teledyne e2v
Simulations and characterisation of the TDI CMOS chip CIS123 Rev.E provided by Te2v.

Theseus CMOS Sensor Development – ESA TDE Activity

Role	Start date	End date	Funding source
Co-investigator	01 Nov 2019	31 Mar 2023	ESA (European Space Agency)
The project aims to develop a new type of X-ray sensor based on CMOS image sensor technology, initially for ESA’s M5 mission candidate Theseus, but with butch broader ranging impact across science and synchrotron science.

[Te2v] CIS123 Rev. D Characterisation

Role	Start date	End date	Funding source
Lead	02 Sep 2019	31 Dec 2019	e2v Teledyne e2v
Characterisation of CIS123 Revision D, a TDI CMOS image sensor developed by Teledyne e2v.

TDI CMOS Device Simulations

Role	Start date	End date	Funding source
Lead	01 May 2019	31 May 2019	e2v Teledyne e2v
Simulations in TCAD of TDI CMOS structures for implementation in manufacturing process by Te2v.

[ATTRACT] Single Photon Visible Light Image Sensors for Science and Technology

Role	Start date	End date	Funding source
Lead	01 Mar 2019	29 Feb 2020	EC (European Commission): FP (inc. Horizon Europe, H2020, ERC);CERN European Council for Nuclear Research (Conseil Européen pour la Recherche Nucléaire)
This project will investigate innovative ways to realise single photon visible light imagers for a number of high growth areas in science and technology. The main objective is to create image sensor designs suitable for adaptive optics systems and low-light level spectroscopic and imaging applications, based on detailed semiconductor and technology device simulations. By detecting and counting each and every photon without any additional noise, these sensors could offer the ultimate performance in imaging, and help us see and discover the unknown. The work will focus on designing of Complementary Metal Oxide Semiconductor (CMOS) image sensors with deep sub-electron readout noise and high frame rate. Reliable single photon imaging from large sensors would offer a breakthrough in performance, and the results of this project are expected to lay the foundations for transformational changes to low-light imaging in science and technology.

[Te2v] : Ruby Heavy Ion Tests

Role	Start date	End date	Funding source
Lead	01 Dec 2018	30 Nov 2019	e2v Teledyne e2v
Teledyne e2v have developed new versions of the EV76C660 and EV76C661 (the Ruby family) CMOS image sensors with increased resistance to single event effects from radiation in space applications. Previous heavy ion tests on the EV76C660 sensor conducted by the CEI have revealed much improved resistance to single event latch-ups. In this project Teledyne e2v are requesting the CEI to perform additional heavy ion testing on the new EV76C661 CMOS image sensor in order to investigate the suitability of the device for space applications.

[Te2v] HiRho image sensor development

Role	Start date	End date	Funding source
Lead	01 Dec 2018	01 Mar 2019	e2v Teledyne e2v
In this project the CEI will carry out Technology CAD (TCAD) modelling to support the design of a 2k x 2k high performance image sensor with increased sensitivity at near-infrared wavelengths. The principle of operation of the sensor was invented at the OU and involves specialised pixel structure that allows the substrate to be reverse biased and fully depleted. The CEI will simulate the geometry, the doping profile and the electrical performance of the pixel to be included in the new imager. The work is done in support of Teledyne e2v (Te2v) from their contract with the European Space Agency.

STFC Open 2018 DTP

Role	Start date	End date	Funding source
Co-investigator	01 Oct 2018	30 Sep 2022	STFC Science & Technology Facilities Council
STFC Open 2018 DTP

[Te2v] ONYX Heavy Ion Testing

Role	Start date	End date	Funding source
Lead	01 Oct 2018	31 Mar 2019	e2v Teledyne e2v
Teledyne e2v have developed the EV76C664 (Onyx) CIS which is part of the same family of CIS as the EV76C660 (Ruby) and EV76C560 (Sapphire) CIS. The CEI has performed extensive TID, TNID and HIT campaigns on both the Ruby and Sapphire CIS and has flown the Sapphire CIS in the C3D instrument on UKube-1 and the C3D2 instrument on AlSat Nano. Teledyne e2v are requesting CEI perform Heavy Ion Testing on the Teledyne e2v EV76C664 (Onyx) CMOS Image Sensor to investigate the suitability of the device for space applications.

TDI CMOS Prototype Camera

Role	Start date	End date	Funding source
Lead	01 Apr 2018	23 Feb 2023	CEOI Centre for Earth Observation Instrumentation
Teledyne-e2v have a new CMOS technology suitable for Time Delay Integration (TDI) operation, commonly used in optical payloads for Earth Observation. In this project, Teledyne-e2v will manufacture these new TDI CMOS devices and they will be integrated and tested by Surrey Satellite Technology (SSTL) Optical Payloads Group and the CEI. The result will be a high-TRL TDI CMOS-based engineering model (EM) camera system integrated with SSTL's newest optical telescope, that could be further developed to a flight model for a future technology demonstration mission (out of scope for this call).

STFC IAA 2017

Role	Start date	End date	Funding source
Co-investigator	01 Aug 2017	30 Sep 2018	STFC Science & Technology Facilities Council
The funding from the STFC under their Impact Accelerator account is being used to strategically focus on translating our space research, developing new opportunities and providing support to foster entrepreneurialism among our academics and researchers. The funding from the 2017 STFC IAA will support projects aimed at: 1. Developing techniques to produce higher resolution remote sensing of surface temperature. 2. Production of a Digital Correlated Double Sampling (DCDS) instrument. 3. Developing techniques to determine the characteristics of ice.

NSTP3-R1/e2v Characterisation of TDI CMOS

Role	Start date	End date	Funding source
Lead	01 Jan 2017	14 Jun 2019	UKSA UK Space Agency
The CEI have been invited by e2v to collaborate on a bid into the UKSA NSTP3-R1 call, with e2v as the lead organisation. The CEI element of this bid is to perform electro-optic characterisation of a new Time Delay Integration (TDI) CMOS image sensor developed by e2v before and after gamma irradiation of the sensor.

ESA p-channel contract change notification

Role	Start date	End date	Funding source
Co-investigator	05 Sep 2016	01 Sep 2017	ESA (European Space Agency)
The CEI have been working under contract to ESA (CLS-404-14) on an investigation in the performance characterisation and radiation testing of p-channel CCDs. This work is now nearing completion and ESA have indicated that they would like to fund an additional study under a contract change notification (CCN). This additional study will focus on the evolution of defects within a back illuminated p-channel and n-channel CCD204 after the devices have been irradiated, side-by-side, and for a period of time after, whilst cold annealing takes place.

CMOS Image Sensors for Precision Astronomy

Role	Start date	End date	Funding source
Lead	01 Apr 2016	31 Mar 2020	STFC Science & Technology Facilities Council
The subject of this project will be high performance CMOS imagers with high quantum efficiency, low noise and high frame rate for demanding science applications such as ground and space-based astronomy. This studentship will contribute to the detailed characterisation and understanding of the complex nature of those sensors, and will help develop imagers with improved characteristics.

JUICE phases B2/C/D

Role	Start date	End date	Funding source
Co-investigator	01 Apr 2015	31 Mar 2021	UKSA UK Space Agency
This phase of the grant is to cover the "build phase" (B2/C/D) of ESA's JUICE mission. The CEI will procure, qualify and test the flight model detectors and supply them to DLR for integration into the flight camera. During this project the CEI will provide design inputs to the JANUS camera consortium, support formal ESA meetings, reviews, and telecons with documentation, study the trade-offs in the use of the sensors, particularly recommending operating temperature and temperature stability, and the strategy for removing prompt electron events from the images. We are also completing the modelling of the effects of electron radiation on mission science and image quality, and will perform qualification radiation damage assessment on the technology with protons, electrons, gammas and heavy ions. The CEI will also perform acceptance radiation damage assessment on devices from the flight wafer.

CMOS Image Sensors with High Quantum Efficiency

Role	Start date	End date	Funding source
Lead	18 Feb 2015	30 Sep 2016	UKSA UK Space Agency
One of the main image sensors for space applications today is the CCD due to its high image quality, low noise and large sensitive area. Through back illumination of fully depleted devices the CCD demonstrates quantum efficiency (QE) above 90% over much of the visible range. Over recent years, new CMOS image technology has been under development and now can achieve similar low noise and large area, however, deep depletion has remained elusive due to the more complex CMOS structure, combined with typically low operating voltages. This project aims to develop the next generation of CMOS image sensors suitable for Earth observation, ground and space-based astronomy, and other science applications requiring high QE in the red and near-infrared parts of the spectrum. The main innovation is the achievement of high QE by full depletion of the thick sensitive semiconductor layer using reverse substrate bias. In this way sensitive detector thickness of 100 µm or more can be realised, instead of the current 5-10 µm thick devices. The development will concentrate on building silicon CMOS image sensors using pinned photodiode photosensitive elements, capable of achieving science-grade imaging performance. The technological advances from this work will allow many space-based imaging instruments to transition from CCD to CMOS devices and benefit from better radiation hardness, higher readout speeds, increased level of integration and lower power dissipation. At the Centre for Electronic Imaging (CEI), based at the Open University, we have performed preliminary modelling and have filed a patent application to enable the construction of fully depleted CMOS image sensors using reverse substrate bias. Under this programme we would aim to design, manufacture and test prototype CMOS image sensors based on our patent application.

Publications

Journal articles

Non-ionizing radiation effects in a soft X-ray CMOS image sensor (2024-07)
Townsend-Rose, Charles; Buggey, Thomas; Ivory, James; Dazzazi, Imane; Stefanov, Konstantin and Hall, David
Journal of Astronomical Telescopes, Instruments, and Systems, 10, Article 36002(3)

Timing and gain performance of Teledyne e2v’s LGADs before and after irradiation (2024-06-18)
Mulvey, J.; Allport, P.; Ball, K.; Bortoletto, D.; Gazi, M.; Glover, J.; Gonella, L.; Jordan, D.; McMahon, S.; Plackett, R.; Stefanov, K.; Villani, E. G. and Watkins, M.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Article 169545 ((Early Access))

Ionising radiation effects in a soft X-ray CMOS image sensor (2024-02)
Townsend-Rose, Charles; Buggey, Thomas; Ivory, James; Stefanov, Konstantin D. and Holland, Andrew D.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1059, Article 169011

CMOS Image Sensor for Broad Spectral Range with >90% Quantum Efficiency (2023-11)
Setälä, Olli E.; Prest, Martin J.; Stefanov, Konstantin D.; Jordan, Douglas; Soman, Matthew R.; Vähänissi, Ville and Savin, Hele
Small, 19, Article 2304001(47)

Electro-optical characterization of a CMOS image sensor optimized for soft x-ray astronomy (2023-10-14)
Townsend-Rose, Charles; Buggey, Thomas; Ivory, James; Stefanov, Konstantin D.; Jones, Lawrence; Hetherington, Oliver; Holland, Andrew D. and Prod’homme, Thibaut
Journal of Astronomical Telescopes, Instruments, and Systems, 9, Article 46001(4)

Pinned Photodiode Imaging Pixel With Floating Gate Readout and Dual Gain (2023)
Stefanov, Konstantin D. and Prest, Martin J.
IEEE Transactions on Electron Devices, 70(6) (pp. 3136-3139)

A Method to Achieve High Dynamic Range in a CMOS Image Sensor Using Interleaved Row Readout (2022-11-15)
Wocial, Thomas; Stefanov, Konstantin D.; Martin, William E.; Barnes, John R. and Jones, Hugh R.A.
IEEE Sensors Journal, 22(22) (pp. 21619-21627)

Preliminary test results of LGADs from Teledyne e2v for the LHC’s High-Luminosity upgrade (2022-10-04)
Mulvey, J.; Allport, P.; Bell, R.; Bortoletto, D.; Gazi, M.; Gonella, L.; Jordan, D.; Kopsalis, I.; McMahon, S.; Plackett, R.; Stefanov, K.; Villani, E.G. and Watkins, M.
Journal of Instrumentation, 17, Article C10001(October)

Characterisation of a soft X-ray optimised CMOS Image Sensor (2022-05)
Heymes, J.; Ivory, J.; Stefanov, K.; Buggey, T.; Hetherington, O.; Soman, M. and Holland, A.
Journal of Instrumentation, 17, Article P05003(5)

Low Gain Avalanche Detector development for the LHC’s High-Luminosity Upgrade at Teledyne e2v (2022)
Allport, P.; Bortoletto, D.; Gazi, M.; Gonella, L.; Hynds, D.; Jordan, D.; Kopsalis, I.; McMahon, S.; Mulvey, J.; Plackett, R.; Stefanov, K. and Villani, E. G.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Article 166876

Proton and Gamma Radiation Effects on a Fully Depleted Pinned Photodiode CMOS Image Sensor (2020-06-19)
Meng, Xiao; Stefanov, Konstantin and Holland, Andrew
IEEE Transactions on Nuclear Science, 67(6) (pp. 1107-1113)

Simulations and Design of a Single-Photon CMOS Imaging Pixel Using Multiple Non-Destructive Signal Sampling (2020)
Stefanov, Konstantin; Prest, Martin J.; Downing, Mark; George, Elizabeth; Bezawada, Naidu and Holland, Andrew
Sensors, 20(7)

Electron Multiplying Low-Voltage CCD With Increased Gain (2018-07)
Stefanov, Konstantin D.; Dunford, Alice and Holland, Andrew D.
IEEE Transactions on Electron Devices, 65(7) (pp. 2990-2996)

Thermal annealing response following irradiation of a CMOS imager for the JUICE JANUS instrument (2018-03-22)
Lofthouse-Smith, D.-D.; Soman, M.R.; Allanwood, E.A.H.; Stefanov, K.D.; Holland, A.D.; Leese, M. and Turner, P.
Journal of Instrumentation, 13, Article C03036(3)

Ageing and proton irradiation damage of a low voltage EMCCD in a CMOS process (2018-02-28)
Dunford, A.; Stefanov, K. and Holland, A.
Journal of Instrumentation, 13, Article C02059

Design and Performance of a Pinned Photodiode CMOS Image Sensor Using Reverse Substrate Bias (2018-01-03)
Stefanov, Konstantin D.; Clarke, Andrew S.; Ivory, James and Holland, Andrew D.
Sensors, 18, Article 118(1)

GravityCam: Wide-field high-resolution high-cadence imaging surveys in the visible from the ground (2018)
Mackay, C.; Dominik, M.; Steele, I. A.; Snodgrass, C.; Jørgensen, U. G.; Skottfelt, J.; Stefanov, K.; Carry, B.; Braga-Ribas, F.; Doressoundiram, A.; Ivanov, V. D.; Gandhi, P.; Evans, D. F.; Hundertmark, M.; Serjeant, S. and Ortolani, S.
Publications of the Astronomical Society of Australia, 35, Article e047 (pp. 1-18)

Characterisation of a novel reverse-biased PPD CMOS image sensor (2017-11-07)
Stefanov, Konstantin; Clarke, Andrew; Ivory, James and Holland, Andrew
Journal of Instrumentation, 12, Article C11009(11)

Evolution and impact of defects in a p-channel CCD after cryogenic proton-irradiation (2017-11)
Wood, Daniel; Hall, David J.; Gow, Jason; Skottfelt, Jesper; Murray, Neil J.; Stefanov, Konstantin and Holland, Andrew D.
IEEE Transactions on Nuclear Science, 64(11) (pp. 2814-2821)

Fully Depleted Pinned Photodiode CMOS Image Sensor With Reverse Substrate Bias (2017-01-03)
Stefanov, Konstantin D.; Clarke, Andrew S. and Holland, Andrew D.
IEEE Electron Device Letters, 38(1) (pp. 64-66)

Comparison of Point Spread Function in p- and n-Channel CCDs (2015-08-07)
Murray, N. J.; Allanwood, E. A. H.; Dryer, B. J.; Weatherill, D. P.; Stefanov, K. D.; Holland, A. D. and Burt, D. J.
Journal of Instrumentation, 10, Article C08007(8)

Fully depleted, thick, monolithic CMOS pixels with high quantum efficiency (2015-04-30)
Clarke, A.; Stefanov, K.; Johnston, N. and Holland, A.
Journal of Instrumentation, 10, Article T04005(4)

Digital CDS for image sensors with dominant white and 1/f noise (2015-04-08)
Stefanov, Konstantin
Journal of Instrumentation, 10, Article P04003(4)

Characterisation of a CMOS charge transfer device for TDI imaging (2015-03-18)
Rushton, J.; Holland, A.; Stefanov, K. and Mayer, F.
Journal of Instrumentation, 10, Article C03027(3)

Non-linear responsivity characterisation of a CMOS Active Pixel Sensor for high resolution imaging of the Jovian system (2015-02-28)
Soman, M.; Stefanov, K.; Weatherill, D.; Holland, A.; Gow, J. and Leese, M.
Journal of Instrumentation, 10, Article C02012(2)

Analytical investigation of correlated charge collection in CCDs (2015-02-02)
Weatherill, D. P.; Stefanov, K. D.; Holland, A. D. and Jordan, D.
Journal of Instrumentation, 10, Article C02002(2)

Optimal digital correlated double sampling for CCD signals (2014-07-03)
Stefanov, K. D. and Murray, N. J.
Electronics Letters, 50(14) (pp. 1022-1024)

A statistical model for signal-dependent charge sharing in image sensors (2014-01)
Stefanov, Konstantin D.
IEEE Transactions on Electron Devices, 61(1) (pp. 110-115)

Simulations of charge transfer in Electron Multiplying Charge Coupled Devices (2014)
Bush, N.; Stefanov, K.; Hall, D.; Jordan, D. and Holland, A.
Journal of Instrumentation, 9, Article C12042(12)

Performance of deep-depletion buried-channel n-MOSFETs for CMOS image sensors (2013-12)
Stefanov, Konstantin D.; Zhang, Zhige; Damerell, Chris; Burt, David and Kar-Roy, Arjun
IEEE Transactions on Electron Devices, 60(12) (pp. 4173-4179)

Design and performance of a CMOS study sensor for a binary readout electromagnetic calorimeter (2011-05)
Ballin, J. A.; Coath, R.; Crooks, J. P.; Dauncey, P. D.; Magnan, A. -M.; Mikami, Y.; Miller, O. D.; Noy, M.; Rajovic, V.; Stanitzki, M.; Stefanov, K. D.; Turchetta, R.; Tyndel, M.; Villani, E. G.; Watson, N. K.; Wilson, J. A. and Zhang, Z.
Journal of Instrumentation, 6, Article P05009(5)

First results with prototype ISIS devices for ILC vertex detector (2010-12-11)
Damerell, C.; Zhang, Z.; John, J. J.; Li, Y.; Nomerotski, A.; Holland, A.; Seabroke, G.; Havranek, M.; Stefanov, K.; Kar-roy, A.; Bell, R.; Burt, D. and Pool, P.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 624(2) (pp. 465-469)

Design and performance of improved Column Parallel CCD, CPC2 (2010-09-01)
Banda, Y.; Coulter, P.; Cussans, D.; Damerell, C.; Devetak, E.; Fopma, J.; Foster, B.; Frost, R.; Gao, R.; Goldstein, J.; Greenshaw, T.; Harder, K.; Hawes, B.; Hillert, S.; Jeffery, B.; John, J. J.; Kundu, N.; Li, Y.; Murray, P.; Nomerotski, A.; Perry, C.; Stefanov, K.; Thomas, S.; Velthuis, J.; Woolliscroft, T.; Worm, S.; Yow, J. and Zhang, Z.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 621(1-3) (pp. 192-204)

Readout chip for Column Parallel CCD, CPR2A (2009-08-21)
Havranek, M.; Murray, P.; Stefanov, K.; Thomas, S.; Damerell, C.; Fopma, J.; Goldstein, J.; Greenshaw, T.; Hawes, B.; Nomerotski, A.; Woolliscroft, T.; Worm, S. and Zhang, Z.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 607(3) (pp. 640-647)

Charge shielding in the In-situ Storage Image Sensor for a vertex detector at the ILC (2009-08-21)
Zhang, Z.; Stefanov, K. D.; Bailey, D.; Banda, Y.; Buttar, C.; Cheplakov, A.; Cussans, D.; Damerell, C.; Devetak, E.; Fopma, J.; Foster, B.; Gao, R.; Gillman, A.; Goldstein, J.; Greenshaw, T.; Grimes, M.; Halsall, R.; Harder, K.; Hawes, B.; Hayrapetyan, K.; Heath, H.; Hillert, S.; Jackson, D.; Pinto Jayawardena, T.; Jeffery, B.; John, J.; Johnson, E.; Kundu, N.; Laing, A.; Lastovicka, T.; Lau, W.; Lintern, A.; Lynch, C.; Mandry, S.; Martin, V.; Murray, P.; Nichols, A.; Nomerotski, A.; Page, R.; Parkes, C.; Perry, C.; O'Shea, V.; Sopczak, A.; Tabassam, H.; Tikkanen, T.; Velthuis, J.; Walsh, R.; Woolliscroft, T. and Worm, S.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 607(3) (pp. 538-543)

Modeling of charge transfer inefficiency in a CCD with high-speed column parallel readout (2009-06)
Sopczak, André; Aoulmit, Salim; Bekhouche, Khaled; Bowdery, Chris; Buttar, Craig; Damerell, Chris; Djendaoui, Dahmane; Dehimi, Lakhdar; Greenshaw, Tim; Koziel, Michal; Maneuski, Dzmitry; Nomerotski, Andrei; Stefanov, Konstantin; Tikkanen, Tuomo; Woolliscroft, Tim and Worm, Steve
IEEE Transactions on Nuclear Science, 56(3) (pp. 1613-1617)

Authored books

CMOS Image Sensors (2022-11)
Stefanov, Konstantin
ISBN : 978-0-7503-3233-0 | Publisher : IOP Publishing | Published : Bristol, UK

Book chapters

CMOS Active Pixel Sensors (2022-11-30)
Stefanov, Konstantin and Holland, Andrew
In: Bambi, Cosimo and Santangelo, Andrea eds. Handbook of X-ray and Gamma-ray Astrophysics. Handbook of X-ray and Gamma-ray Astrophysics (pp. 1-26)
ISBN : 978-981-16-4544-0 | Publisher : Springer | Published : Singapore

CMOS and CCD image sensors for space applications (2020)
Jerram, P. and Stefanov, K.
In: Durini, Daniel ed. High Performance Silicon Imaging (Second Edition): Fundamentals and Applications of CMOS and CCD Sensors. Woodhead Publishing Series in Electronic and Optical Materials (pp. 255-287)
ISBN : 978-0-08-102434-8 | Publisher : Woodhead Publishing

Conference items

Transfer gate effects on the dark current in pinned photodiode image sensors (2024-08-27)
Stefanov, Konstantin D. and Buggey, Thomas W.
In : X-Ray, Optical, and Infrared Detectors for Astronomy XI (16-21 Jun 2024, Yokohama, Japan)

Non-ionising radiation effects in a soft X-ray CMOS image sensor (2024)
Townsend-Rose, Charles; Buggey, Thomas W.; Ivory, James M.; Dazzazi, Imane; Stefanov, Konstantin D. and Hall, David J.
In : SPIE Astronomical Telescopes + Instrumentation, 2024 (16-22 Jun 2024, Yokohama, Japan)

Assessing the suitability of CIS220 for low light astronomy (2024)
Ivory, James M.; Smith, Phillipa; Skottfelt, Jesper M.; Stefanov, Konstantin D.; Buggey, Thomas W.; Prod'Homme, Thibaut and Hall, David J.
In : Proc. SPIE 13103, X-Ray, Optical, and Infrared Detectors for Astronomy XI, 131031I (16-19 Jun 2024, Yokohama, Japan)

Improved QE in CMOS image sensors with nano-black antireflection layer (2023-05-21)
Prest, Martin J.; Setälä, Olli; Stefanov, Konstantin D.; Vähänissi, Ville; Savin, Hele and Jordan, Douglas
In : 2023 International Image Sensor Workshop (21-25 May 2023, Crieff, Scotland)

High Dynamic Range Pinned Photodiode Pixel with Floating Gate Readout and Dual Gain (2023-05)
Stefanov, Konstantin and Prest, Martin J.
In : 2023 International Image Sensor Workshop (21-25 May 2023, Crieff, Scotland)

Characterization, quantum efficiency, and radiation hardness of a CMOS image sensor optimized for soft x-ray astronomy (2023)
Townsend-Rose, Charles; Buggey, Thomas; Ivory, James; Stefanov, Konstantin D.; Jones, Lawrence; Hetherington, Oliver and Holland, Andrew D.
In : SPIE Optical Engineering + Applications (20-24 Aug 2023, San Diego, California, United States)

A CMOS image sensor for soft x-ray astronomy (2022)
Stefanov, Konstantin; Townsend-Rose, Charles; Buggey, Thomas; Ivory, James; Hetherington, Oliver; Holland, Andrew; Heymes, Julian; Pratlong, Jérôme; Tsiolis, Georgios; Morris, David; Minoglou, Kyriaki; Prod'homme, Thibaut and Soman, Matthew
In : SPIE Astronomical Telescopes + Instrumentation (17-23 Jul 2022, Montreal, Canada)

Mitigating charge spill-back induced image lag with a multi-level transfer gate pulse in PPD image sensors (2020-12-13)
Ivory, James; Stefanov, Konstantin D. and Holland, Andrew D.
In : SPIE Astronomical Telescopes + Instrumentation (14-18 Dec 2020, Online)

Quantum efficiency of the CIS115 in a radiation environment (2020)
Crews, Chiaki; Soman, Matthew; Allanwood, Edgar; Stefanov, Konstantin; Leese, Mark; Turner, Peter and Holland, Andrew
In : X-Ray, Optical, and Infrared Detectors for Astronomy IX (14-18 Dec 2020, Online)

Development of a photon-counting near-fano-limited x-ray CMOS image sensor for THESEUS' SXI (2020)
Heymes, Julian; Stefanov, Konstantin; Soman, Matthew; Gorret, Davide; Hall, David; Minoglou, Kyriaki; Morris, David; Pratlong, Jérôme; Prod'homme, Thibaut; Tsiolis, Georgios and Holland, Andrew
In : SPIE Astronomical Telescopes + Instrumentation 2020 (14-18 Dec 2020, Online only)

Predicting the effect of radiation damage on dark current in a space-qualified high performance CMOS image sensor (2019)
Crews, C.; Soman, M. R.; Lofthouse-Smith, D. D.; Allanwood, E. A. H.; Stefanov, K. D.; Leese, M.; Turner, P. and Holland, A.
In : 21st International Workshop on Radiation Imaging Detectors (7-12 Jul 2019, Crete, Greece) (C11008-C11008)

Radiation Hardness Study on a Fully Depleted Pinned Photodiode CMOS Image Sensor (2019)
Meng, Xiao; Stefanov, Konstantin; Holland, Michael and Holland, Andrew
In : 2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) (26 Oct 2019-2 Nov 2019, Manchester, UK) (pp. 1-2)

Image lag optimisation in a 4T CMOS image sensor for the JANUS camera on ESA's JUICE mission to Jupiter (2018-07-16)
Lofthouse-Smith, D.-D.; Soman, M. R.; Allanwood, E. A. H.; Stefanov, K. D.; Holland, A. D.; Leese, M. and Turner, P.
In : SPIE 10709, High Energy, Optical, and Infrared Detectors for Astronomy VIII (10-15 Jun 2018, Austin, Texas)

PSF and non-uniformity in a monolithic, fully depleted, 4T CMOS image sensor (2018-07-12)
Ivory, James M.; Stefanov, Konstantin D.; Turner, Peter and Holland, Andrew D.
In : SPIE Astronomical Telescopes + Instrumentation, 2018 (10-13 Jun 2018, Austin, Texas, US)

The operational characteristics and potential applications of a low voltage EMCCD in a CMOS process (2018-07-12)
Dunford, Alice; Stefanov, Konstantin D. and Holland, Andrew D.
In : SPIE Astronomical Telescopes and Instrumentation. (10-15 Jun 2018, Austin, Texas, United States) (p 84)

Evolution of proton-induced defects in a cryogenically irradiated p-channel CCD (2017-11-02)
Wood, Daniel; Hall, David; Gow, Jason; Murray, Neil; Stefanov, Konstantin and Holland, Andrew
In : 16th European Conference on Radiation and Its Effects on Components and Systems (RADECS 2016) (19-23 Sep 2016, Bremen)

Fully Depleted, Monolithic Pinned Photodiode CMOS Image Sensor Using Reverse Substrate Bias (2017-07-31)
Stefanov, Konstantin D.; Clarke, Andrew S.; Ivory, James and Holland, Andrew D.
In : International Image Sensor Workshop (May 30-2 Jun 2017, Hiroshima, Japan) (pp. 109-112)

e2v CMOS and CCD sensors and systems for astronomy (2017-07-05)
Jorden, P. R.; Jerram, P. A.; Fryer, M. and Stefanov, K. D.
In : Precision Astronomy with Fully Depleted CCDs (PACCD2016) (1-2 Dec 2016, Brookhaven National Laboratory, USA)

Single event effects in 0.18 μm CMOS image sensors (2016-08-05)
Rushton, Joseph E.; Stefanov, Konstantin D.; Holland, Andrew D.; Bugnet, Henri; Mayer, Frederic; Cordrey-Gale, Matthew and Endicott, James
In : High Energy, Optical, and Infrared Detectors for Astronomy VII (26 Jun - 1 Jul 2016, Edinburgh, United Kingdom)

Validation of NIEL for >1MeV electrons in silicon using the CCD47-20 (2016-08-05)
Dryer, B.; Smith, P.; Nuns, T.; Murray, N.; Stefanov, K. D.; Gow, J. P. D.; Burgon, R.; Hall, D. J. and Holland, A. D.
In : High Energy, Optical, and Infrared Detectors for Astronomy VII (26 Jun - 1 Jul 2016, Edinburgh, United Kingdom)

Electro-optic and radiation damage performance of the CIS115, an imaging sensor for the JANUS optical camera on-board JUICE (2016-08-01)
Soman, M. R.; Allanwood, E. A. H.; Holland, A. D.; Stefanov, K.; Pratlong, J.; Leese, M.; Gow, J. P. D. and Smith, D. R.
In : High Energy, Optical, and Infrared Detectors for Astronomy VII (26 Jun 2016, Edinburgh)

Low Voltage Electron Multiplying CCD in a CMOS Process (2016-07-27)
Dunford, Alice; Stefanov, Konstantin and Holland, Andrew
In : SPIE Astronomical Telescopes + Instrumentation (AS16) (26 Jun - 1 Jul 2016, Edinburgh, UK)

Fully depleted and backside biased monolithic CMOS image sensor (2016-07-27)
Stefanov, Konstantin D.; Clarke, Andrew S. and Holland, Andrew D.
In : High Energy, Optical, and Infrared Detectors for Astronomy VII (25-30 Jun 2016) (p 991513)

A global shutter CMOS image sensor for hyperspectral imaging (2015-09-22)
Stefanov, Konstantin D.; Dryer, Ben. J.; Hall, David J.; Holland, Andrew D.; Pratlong, Jérôme; Fryer, Martin and Pike, Andrew
In : UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VII (9 Aug 2015, San Diego, CA)

Proton-induced Random Telegraph Signal in the CMOS imaging sensor for JANUS, the visible imaging telescope on JUICE (2015-09-22)
Winstone, G. P.; Soman, M. R.; Allanwood, E. A. H.; Holland, A. D.; Gow, J. P. D.; Stefanov, K. and Leese, M.
In : UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VII (9 Aug 2015, San Diego, CA) (96020N)

A CMOS TDI image sensor for Earth observation (2015-09-01)
Rushton, Joseph E.; Stefanov, Konstantin D.; Holland, Andrew D.; Endicott, James; Mayer, Frederic and Barbier, Frederic
In : Nanophotonics and Macrophotonics for Space Environments IX (13-15 Aug 2015, San Diego, CA)

Proton irradiation of the CIS115 for the JUICE mission (2015-09)
Soman, M. R.; Allanwood, E. A. H.; Holland, A. D.; Winstone, G. P.; Gow, J. P. D.; Stefanov, K. and Leese, M.
In : UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VII (9 Aug 2015, San Diego, CA)

Models for dynamic correlated charge collection effects in thick CCDs (2015-08)
Weatherill, Daniel P.; Stefanov, Konstantin; Jordan, Douglas; Holland, Andrew and Kotov, Ivan V.
In : UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VII (09-13 Aug 2015, San Diego, CA)

Modelling and testing the x-ray performance of CCD and CMOS APS detectors using numerical finite element simulations (2014-07-23)
Weatherill, Daniel P.; Stefanov, Konstantin D.; Greig, Thomas A. and Holland, Andrew D.
In : SPIE Astronomical Telescopes and Instrumentation (22-25 Jun 2014, Montreal)

Assessment of the performance and radiation damage effects under cryogenic temperatures of a P-channel CCD204s (2014)
Murray, Neil J.; Holland, Andrew D.; Gow, Jason P. D.; Hall, David J.; Stefanov, Konstantin D.; Dryer, Ben J.; Barber, Simeon and Burt, David J.
In : High Energy, Optical, and Infrared Detectors for Astronomy VI (22-27 Jul 2014, Montréal, Quebec)

Design and characterisation of the new CIS115 sensor for JANUS, the high resolution camera on JUICE (2014)
Soman, Matthew; Holland, Andrew; Stefanov, Konstantin; Gow, Jason; Leese, Mark; Pratlong, Jérôme and Turner, Peter
In : High Energy, Optical, and Infrared Detectors for Astronomy VI (22-25 Jun 2014, Montreal)

Performance of buried channel n-type MOSFETs in 0.18-μm CMOS image sensor process (2013-09-26)
Stefanov, Konstantin D.; Zhang, Zhige; Damerell, Chris; Burt, David and Kar-Roy, Arjun
In : UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XVIII (25 Aug 2013, San Diego)

Multi-level parallel clocking of CCDs for: improving charge transfer efficiency, clearing persistence, clocked anti-blooming, and generating low-noise backgrounds for pumping (2013-09-26)
Murray, Neil J.; Burt, David J.; Holland, Andrew D.; Stefanov, Konstantin D.; Gow, Jason P. D.; MacCormick, Calum; Dryer, Ben J. and Allanwood, Edgar A. H.
In : UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VI (25-26 Aug 2013, San Diego)

Point-spread function and photon transfer of a CCD for space-based astronomy (2013)
Allanwood, Edgar A. H.; Murray, Neil J.; Stefanov, Konstantin D.; Burt, David J. and Holland, Andrew D.
In : UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VI, (25-26 Aug 2013, San Diego)

Total ionizing dose effects on I-V and noise characteristics of MOS transistors in a 0.18 μm CMOS Image Sensor process (2013)
Greig, Thomas; Stefanov, Konstantin; Holland, Andrew; Clarke, Andrew; Burt, David and Gow, Jason
In : 14th European Conference on Radiation and Its Effects on Components and Systems (RADECS) (23-27 Sep . 2013, Oxford)

Other

Imaging device (2021-06-23)
Stefanov, Konstantin

Image Sensor (2017-11-09)
Stefanov, Konstantin and Holland, Andrew

Image Sensor (2017-10-19)
Jerram, Paul and Stefanov, Konstantin

CMOS image sensor (2015-09-16)
Stefanov, Konstantin

Smart power source (2013-07-04)
Bourilkov, Jordan; Specht, Steven; Coronado, Sergio; Stefanov, Konstantin and Ayoz, Suat

Sensor Signal Sampling (2013-05-16)
Colby, Edward; Storkey, Matthew; Healy, David and Stefanov, Konstantin

Faculty of Science, Technology, Engineering & Mathematics

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Dr Konstantin Stefanov

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