Noise performance of high-efficiency germanium quantum dot photodetectors

Abstract

We report on the noise analysis of high performance germanium quantum dot (Ge QD) photodetectors with responsivity up to ∼2 A/W and internal quantum efficiency up to ∼400%, over the 400–1100 nm wavelength range and at a reverse bias of −10 V. Photolithography was performed to define variable active-area devices that show suppressed dark current, leading to a higher signal-to-noise ratio, up to 105, and specific detectivity D*≃6×1012 cm Hz 1/2 W−1. These figures of merit suggest Ge QDs as a promising alternative material for high-performance photodetectors working in the visible to near-infrared spectral range.