Wavelength selective silicon avalanche photodiodes with controlled wide spectral gain by integrating photon-trapping microstructures

Abstract

Silicon avalanche photodiodes (Si-APD) are widely explored due to their high sensitivity, rapid response time, high quantum efficiency, intrinsic multiplication gain, and low signal-to-noise ratio. We present an experimental demonstration of a wavelength selective APD stack epitaxially grown in two different doping orders:–1) N-on-P and 2) P-on-N.We present a performance comparison between N-on-P and P-on-N based on the quantum external efficiency (EQE), Ion/Ioff ratio, and the reverse biased dark state leakage current. By reversing the doping from P-on-N to N-on-P, we show a 40% increase in the EQE. By introducing the photon-trapping hole array we show a 60% improvement in the EQE. We have utilized a low temperature (450oC) forming gas (5% H2 and 95% N2) annealing process to passivate the surface states and show a dark state leakage current improvement from sub- 10nA to sub-1nA current range. The proposed devices are complementary metal oxide semiconductor process compatible and can enable ‘detectors-on-chip’ technology for numerous applications such as internet-of-things, data communication, biomedical imaging, high-speed cloud computing, remote sensing, as well as single-photon detection.