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Studies of spatial uniformity and jitter in SiC UV SPADs



Joshua Bienfang, Edwin J. Heilweil, Anand Sampath, Gregory Garrett, Jonathan Shuster, Jeremy Smith, Michael Derenge, Daniel Habersat, Reza Gandhi, Sergei Dolinsky, Enrico Bellotti, michael wrabeck


Ultraviolet single-photon avalanche detectors (UV-SPAD) that are low cost, size, weight, and power as well as resilient to shock, high temperatures and stray magnetic fields have a number of applications. SiC is attractive for UV SPADs as it is inherently blind to visible light, and Geiger mode as well as high-gain linear-mode devices have been demonstrated. However, issues remain regarding bias dependence of spatial uniformity of detection efficiency (DE) and responsivity, as well as the temporal resolution, or jitter, in Geiger mode. Over a wide range of device structures (p- vs. n- illuminated) we observe a decrease in responsivity spatial uniformity as gain increases from 100 to 105 that improves thereafter. The spatial dependence of the DE in Geiger mode agrees with linear-mode results for gain >105. This presents in all devices as an "optically-dead" region on one-side of the detector whose extent varies with operating conditions, independent of contact geometry and device layout.. Jitter measurements at 267 nm illumination show a full width at half maximum below 92 ps which is significantly lower than previously reported and potentially an upper-bound due to passive quenching as well as the spatial non-uniformity. These observations will be discussed within the context of differing explanations for observed spatial non-uniformity reported for effects occurring at different operating conditions (increasing with gain due to dopant variation or decreasing with excess bias due to crystal anisotropy and carrier screening).
Proceedings Title
Proceedings of SPIE Defense and Commercial Sensing 2023 - Advanced Photon Counting Techniques XVII
Conference Dates
April 30-May 4, 2023
Conference Location
Orlando, FL, US
Conference Title
SPIE Defense and Commercial Sensing Meeting - Advanced Photon Counting Techniques XVII


ultraviolet avalanche photodiodes, spatial uniformity, jitter, Geiger-mode, single-photon avalanche diode, single-photon detection


Bienfang, J. , Heilweil, E. , Sampath, A. , Garrett, G. , Shuster, J. , Smith, J. , Derenge, M. , Habersat, D. , Gandhi, R. , Dolinsky, S. , Bellotti, E. and wrabeck, M. (2023), Studies of spatial uniformity and jitter in SiC UV SPADs, Proceedings of SPIE Defense and Commercial Sensing 2023 - Advanced Photon Counting Techniques XVII, Orlando, FL, US, [online],, (Accessed May 22, 2024)


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Created June 15, 2023, Updated June 28, 2023