Analysis of the Electric Field and Photocurrent Densities in Germanium-on-Silicon Single-Photon Avalanche Diodes

Dave Muir; Lisa Saalbach; Mrudul Modak; Fiona Fleming; Xin Yi; Gerald S. Buller

doi:10.1109/ted.2025.3617900

Analysis of the Electric Field and Photocurrent Densities in Germanium-on-Silicon Single-Photon Avalanche Diodes

Dave Muir, Lisa Saalbach, Mrudul Modak, Fiona Fleming, Xin Yi, Gerald S. Buller

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Abstract

This study presents a modeling analysis of the electric field and current distribution in germanium-on-silicon (Ge-on-Si) single-photon avalanche diode (SPAD) detectors. This analysis will provide a detailed examination of current flow and electric field behavior within the SPAD, emphasizing the significant impact of sidewall effects. The simulations of the SPAD’s electric field reveal an unexpected increase in current levels in the photocurrent–voltage characteristics, which is attributable to sidewall effects rather than punchthrough. Similar current increases have been observed in other avalanche photodiodes and SPADs across various semiconductor materials and microstructures. To the best of our knowledge, no previously published work has explored the underlying mechanism behind this anomalous current behavior. Additionally, this study simulates the influence of different materials, doping profiles, and structural configurations, offering insights into strategies for achieving a more controlled photon-induced avalanche response in Ge-on-Si SPADs.

Original language	English
Pages (from-to)	1-7
Number of pages	7
Journal	IEEE Transactions on Electron Devices
Early online date	10 Nov 2025
DOIs	https://doi.org/10.1109/ted.2025.3617900
Publication status	E-pub ahead of print - 10 Nov 2025

Keywords

Avalanche photodiode
device design
edge effects
electric current
electric field
germanium-on-silicon (Ge-on-Si)
modeling
punchthrough
single-photon avalanche diode (SPAD)

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Electrical and Electronic Engineering

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title = "Analysis of the Electric Field and Photocurrent Densities in Germanium-on-Silicon Single-Photon Avalanche Diodes",

abstract = "This study presents a modeling analysis of the electric field and current distribution in germanium-on-silicon (Ge-on-Si) single-photon avalanche diode (SPAD) detectors. This analysis will provide a detailed examination of current flow and electric field behavior within the SPAD, emphasizing the significant impact of sidewall effects. The simulations of the SPAD{\textquoteright}s electric field reveal an unexpected increase in current levels in the photocurrent–voltage characteristics, which is attributable to sidewall effects rather than punchthrough. Similar current increases have been observed in other avalanche photodiodes and SPADs across various semiconductor materials and microstructures. To the best of our knowledge, no previously published work has explored the underlying mechanism behind this anomalous current behavior. Additionally, this study simulates the influence of different materials, doping profiles, and structural configurations, offering insights into strategies for achieving a more controlled photon-induced avalanche response in Ge-on-Si SPADs.",

keywords = "Avalanche photodiode, device design, edge effects, electric current, electric field, germanium-on-silicon (Ge-on-Si), modeling, punchthrough, single-photon avalanche diode (SPAD)",

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AU - Fleming, Fiona

AU - Yi, Xin

AU - Buller, Gerald S.

PY - 2025/11/10

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N2 - This study presents a modeling analysis of the electric field and current distribution in germanium-on-silicon (Ge-on-Si) single-photon avalanche diode (SPAD) detectors. This analysis will provide a detailed examination of current flow and electric field behavior within the SPAD, emphasizing the significant impact of sidewall effects. The simulations of the SPAD’s electric field reveal an unexpected increase in current levels in the photocurrent–voltage characteristics, which is attributable to sidewall effects rather than punchthrough. Similar current increases have been observed in other avalanche photodiodes and SPADs across various semiconductor materials and microstructures. To the best of our knowledge, no previously published work has explored the underlying mechanism behind this anomalous current behavior. Additionally, this study simulates the influence of different materials, doping profiles, and structural configurations, offering insights into strategies for achieving a more controlled photon-induced avalanche response in Ge-on-Si SPADs.

AB - This study presents a modeling analysis of the electric field and current distribution in germanium-on-silicon (Ge-on-Si) single-photon avalanche diode (SPAD) detectors. This analysis will provide a detailed examination of current flow and electric field behavior within the SPAD, emphasizing the significant impact of sidewall effects. The simulations of the SPAD’s electric field reveal an unexpected increase in current levels in the photocurrent–voltage characteristics, which is attributable to sidewall effects rather than punchthrough. Similar current increases have been observed in other avalanche photodiodes and SPADs across various semiconductor materials and microstructures. To the best of our knowledge, no previously published work has explored the underlying mechanism behind this anomalous current behavior. Additionally, this study simulates the influence of different materials, doping profiles, and structural configurations, offering insights into strategies for achieving a more controlled photon-induced avalanche response in Ge-on-Si SPADs.

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KW - device design

KW - edge effects

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KW - punchthrough

KW - single-photon avalanche diode (SPAD)

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JF - IEEE Transactions on Electron Devices

ER -

Analysis of the Electric Field and Photocurrent Densities in Germanium-on-Silicon Single-Photon Avalanche Diodes

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Keywords

ASJC Scopus subject areas

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