Surface-Illuminated Interdigitated Ge-on-Si Avalanche Photodiode With Separated Ge Absorption, Si Multiplication, and Lateral Field Engineering
Abstract
This work presents a surface-illuminated lateral Ge-on-Si interdigitated separate-absorption-charge-multiplication (SACM) avalanche photodiode for 1550-nm detection. The intrinsic-region spacing, P- charge-control width, and finger geometry are engineered to suppress high-field penetration toward the Ge/Si heterointerface and localize avalanche multiplication in Si. Simulations show that wider charge-control or intrinsic regions reduce fixed-bias dark current and shift avalanche onset to higher reverse bias. Among the tested structures, the intrinsic-region spacing/P- charge-control width of 0.5/0.15 μm achieved a peak responsivity of 11.81 A/W at 1550 nm. At a -20 V applied voltage, it exhibited a multiplication gain of 3.796, a 3-dB bandwidth of 7.13 GHz, and a matched-bias gain-bandwidth product of 27.07 GHz. Optical-power-dependent measurements also show avalanche-gain compression consistent with space-charge screening. These results demonstrate effective lateral-field engineering for high-speed, surface-illuminated Ge-on-Si APDs.
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BibTeX
@misc{clewis2026surfaceilluminated,
title = {{Surface-Illuminated Interdigitated Ge-on-Si Avalanche Photodiode With Separated Ge Absorption, Si Multiplication, and Lateral Field Engineering}},
author = {Mason Clewis and Kuang-Yun Tu and Ching-Yu Hsu and Zingway Pei},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.37593},
eprint = {2610.37593},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.37593},
}
RIS
TY - UNPB
TI - Surface-Illuminated Interdigitated Ge-on-Si Avalanche Photodiode With Separated Ge Absorption, Si Multiplication, and Lateral Field Engineering
AU - Mason Clewis
AU - Kuang-Yun Tu
AU - Ching-Yu Hsu
AU - Zingway Pei
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.37593
UR - https://arxiv.org/abs/2610.37593
AB - This work presents a surface-illuminated lateral Ge-on-Si interdigitated separate-absorption-charge-multiplication (SACM) avalanche photodiode for 1550-nm detection. The intrinsic-region spacing, P^- charge-control width, and finger geometry are engineered to suppress high-field penetration toward the Ge/Si heterointerface and localize avalanche multiplication in Si. Simulations show that wider charge-control or intrinsic regions reduce fixed-bias dark current and shift avalanche onset to higher reverse bias. Among the tested structures, the intrinsic-region spacing/P^- charge-control width of 0.5/0.15 μm achieved a peak responsivity of 11.81 A/W at 1550 nm. At a -20 V applied voltage, it exhibited a multiplication gain of 3.796, a 3-dB bandwidth of 7.13 GHz, and a matched-bias gain-bandwidth product of 27.07 GHz. Optical-power-dependent measurements also show avalanche-gain compression consistent with space-charge screening. These results demonstrate effective lateral-field engineering for high-speed, surface-illuminated Ge-on-Si APDs.
ER -