Analysis of type-II InAs/GaSb superlattice mid-wavelength infrared p-i-n photodetector using device simulation

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 responsibility. The main objective of this work is to understand and analyze the electrical performance of InAs/GaSb type-II superlattice (SL) IR detectors using a device simulator especially focusing on the dark current characteristics. Physical parameters such as the effective density of states 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 photodetector depends on the SL thickness ratio even with a similar cut-off wavelength due to the difference in the intrinsic carrier density. The InAs-rich SL detectors exhibit smaller dark current than the GaSb-rich ones, which is qualitatively consistent with the previously reported experimental data.