Influence of the period thickness and composition on the electro-optical properties of type-II InAs/GaSb midwave infrared superlattice photodetectors

Type-II Superlattice Heterojunction Photodetector with Optoelectronic Characterization and Analytical/ Numerical Simulation

“…With type-II InAs/GaSb superlattices, the goal of this section is to provide the TCAD simulation and computation of the electrical performance, in particular, dark current and complete device band structure with various sets of parameters such as composition, doping, and thickness of each layer. As reported in a recent report [27], choosing different period compositions for a given wavelength demonstrates the strong influence of the InAs/GaSb superlattice period thickness and composition on can boost the photodetector performance and material properties [27]. With an asymmetric superlattice period with thicker InAs layer than GaSb layer, the dark current can be reduced by a factor 4 compared to a symmetric superlattice period (equivalent thickness of both films), showing the same cut-off wavelength at 5 um at 77 K.…”

Structural and optical characterization of InAs/GaSb type-II superlattices: Influence of the change in InAs and GaSb layer thicknesses for fixed InSb-like interfaces

“…On the other hand, it becomes smaller as the InAs thickness changes from 7 to 9 ML for fixed GaSb thickness at 9 ML. Note that the sharpness of the photoresponse cut-off is an indication of the carrier localization and can be modified mainly by the width of the conduction miniband [12,17]. It depends on the width of the valance miniband as well, but the effect is not as distinguished for comparable changes due to the heavier carrier effective mass in the valance band.…”

“…Therefore, for strain and band gap engineering, the individual InAs and GaSb layer thicknesses in each period need to be considered as control parameters when designing a new SL structure. The thickness of a superlattice period also affects the steepness of the photoresponse near the band edge because of the modification of the carrier localization [12,17]. In this article, we studied a group of five InAs/GaSb type-II SL photodetector structures where the layer thicknesses have been systematically changed by keeping the same interface transitions.…”

Identification of a limiting mechanism in GaSb-rich superlattice midwave infrared detector

“…17,18 For a better understanding of the impact of the GaSb content, we have recently studied the influence of the InAs/ GaSb SL period composition and the thickness on the material and device properties. 19,20 We found that the SL period mainly composed of GaSb (hereto referred to as "GaSbrich") has a higher current density than the SL structure mainly composed of InAs ("InAs-rich") having the same cut-off wavelength of 5 lm at 77 K. The current density difference between these MWIR structures is extremely large with almost a factor of 50.…”

“…19 Nevertheless, a possibility is that the molecular beam epitaxy (MBE) growth conditions used for the InAs/ GaSb SL are not suitable for the GaSb-rich SL, resulting in extremely low lifetimes. The SL growth temperature is usually 400 C in order to maintain a good quality of the InSblike interfaces.…”