Monolithic Germanium Tin on Si Avalanche Photodiodes

TL;DR

This paper reports the first monolithic integration of germanium-tin on silicon avalanche photodiodes, achieving high responsivity and gain for infrared detection between 1500-1700 nm, with promising temperature performance.

Contribution

It introduces a novel monolithic GeSn/Si APD design with effective carrier transport and demonstrates high responsivity and gain at infrared wavelengths.

Findings

Saturated primary responsivity of 0.3 A/W at 1550 nm before avalanche breakdown.

Maximum multiplication gain of 4.5 at 77 K and 1.4 at 250 K.

Spectral response covers 1500 to 1700 nm.

Abstract

We demonstrate monolithically grown germanium-tin (GeSn) on silicon avalanche photodiodes (APDs) for infrared light detection. A relatively thinner Ge buffer design was adopted to allow effective photo carriers to transport from the GeSn absorber to the Si multiplication layer such that clear punch-through behavior and a saturated primary responsivity of 0.3 A/W at 1550 nm were observed before avalanche breakdown in GeSn/Si APDs for the first time. The spectral response covers 1500 to 1700 nm. The measured punch-through and breakdown voltages are 15 and 17 V, respectively. Undisputed multiplication gain was obtained with the maximum value of 4.5 at 77 K, and 1.4 at 250 K, directly in reference to the saturated primary responsivity from the same device rather than a different GeSn p-i-n photodiode in previous reports. A peak responsivity was measured as 1.12 A/W at 1550 nm and 77 K.