Simulation of dark current characteristics of type-II InAs/GaSb superlattice mid-wavelength infrared p-i-n photodetector

• Published in: Japanese Journal of Applied Physics 2019-04, Vol.58 (4), p.44002
• Main Authors: Thi, Yen. Le, Kamakura, Yoshinari, Mori, Nobuya
• Format: Article
• Language: English
• Subjects: Carrier density; Computer simulation; Cut off wavelength; Dark current; Indium arsenides; Leakage current; Photodiodes; Photometers; Photosensitivity; Physical properties; Superlattices; Thickness ratio; Two dimensional models
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/1347-4065/ab03ca

For photosensitive devices such as infrared (IR) photodetectors, dark current is an important mechanism limiting the performance because it causes a decrease in the signal-to-noise ratio and the responsivity. The main objective of this work is to understand and analyze the InAs/GaSb type-II superlattice (SL) IR photodiode using a device simulator especially focusing on the dark current characteristics. Physical parameters such as the effective density of states and the effective masses are extracted from the k p band calculation, and included into a two-dimensional device simulator based on the drift-diffusion model. Simulation results demonstrate that the leakage current of the IR photodiode depends on the SL thickness ratio even with the same cut-off wavelength. In the low reverse bias conditions, the "InAs-rich" SL detectors exhibit smaller dark current than the "GaSb-rich" ones, which originates from the difference in the intrinsic carrier density. On the other hand, under the higher voltage and the higher doping level, the larger effective mass of "GaSb-rich" SL can suppress the dark current caused by the tunneling-related leakage mechanisms.