Minimization of dark currents through Type-II Superlattice infrared photodetectors in the MWIR region

Type-II Superlattice (T2SL) photodetectors are at the forefront of optoelectronic detector technology, primarily attributed to their excellent band gap tunability and outstanding optoelectronic characteristics. However, the presence of dark current necessitates the use of an extra cryogenic setup and limits the detector’s performance. To understand the minimization of dark currents, we analyze the dark current characteristics of a 10monolayer (ML) /10ML InAs/GaSb T2SL p-i-n photodetector, simulated in a reverse bias voltage range at 77K. The doping concentration for the active region and the value of the minority carrier lifetime is selected as 5.5 X 10¹⁵ cm^-3 and 40ns [1] respectively. With an increase in the thickness of the active region, we observe a decrease in the electric field within it. Consequently, we achieve a remarkable reduction in the band-to-band tunneling current density, decreasing from 8.5 X 10^-1 A/cm² to 2.3 X 10^-3 A/cm² and we observe that the trap-assisted tunneling current density decreases from 8.25 X 10^-4 A / cm² to 7.5 X 10^-5 A / cm² as we increase the thickness from 300nm to 700nm. The detailed computational models developed here establish the roles of various components of the dark currents in conjunction with the details of confinement effects, thereby setting a stage for the analysis of current generation photodetector devices.

References:

[1] Le Thi, Yen, et.al., Japanese Journal of Applied Physics 58.4 (2019): 044002.