Short-period InAs∕GaSb type-II superlattices for mid-infrared detectors

Abstract

Using a newly developed envelope function approximation model that includes interface effects, several InAs∕GaSb Type-II superlattices (SLs) were designed for the 4μm detection threshold. The present model predicts that a given threshold can be reached with a wide range of progressively thinner SL periods and these thinner designs hold a promise of higher mobilities and longer Auger lifetimes, thus higher detector operating temperatures. The proposed SL structures were grown by molecular-beam epitaxy with slow growth rates. As predicted, the band gaps of SLs determined by low-temperature photoluminescence remained constant around 330meV for the samples in the period range from 50.6to21.2Å.

Short‐period InAs/GaSb superlattices for mid‐infrared photodetectors

“…Recently, superlattices (SLs) based on alternating layers of InAs and GaSb have been a promising alternative due to their type-II band alignment [3] In type-II SLs, intraband transitions can occur between the valence band states localized in GaSb layers and the itinerant conduction band states centered in InAs. By varying the layer widths within a shorter range (periods 60 Å or below), the band gaps can be easily tuned to the mid-IR detection range (3-5 µm) [4][5][6][7]. Recently, we showed [5,8] that very short-period SLs with a period as small as a few monolayers can have several properties beneficial for higher operating temperatures.…”

Hierarchically constrained carrier dynamics in red-LED illuminated type-II InAs/GaSb superlattices

“…11 The SLs were grown 6,32,33 by molecular beam epitaxy on unintentionally doped p-type GaSb substrates with the substrate temperatures set at around 390 C, and the V/III beam flux ratio set at approximately 3 for both GaSb and InAs. Each growth began with an approximately 0.3 lmthick GaSb buffer layer and was followed by a 0.5 lm-thick SL.…”

“…[1][2][3][4][5][6][7][8][9][10] While experimenting with various growth parameters, we found that some samples grown under special conditions exhibited persistent photo-effects upon illumination with a red-light emitting diode (LED). 11 We exploited the resulting variability in carrier density and carrier type to study the in-plane carrier mobility in InAs/GaSb SLs as a function of carrier density.…”

Transport studies of MBE-grown InAs/GaSb superlattices

“…It is well known that native acceptors give rise to intrin− sically p−type GaSb layers while native donors give rise to intrinsically n−type InAs layers [17] Therefore, InAs/GaSb SLs for longer−wavelength IR detection (e.g., SL3) in which InAs layers are wider than GaSb layers tend to be n−type while InAs/GaSb SLs for mid−wavelength IR detection in which GaSb layers are wider than InAs layers -tend to be p−type. In our study, as grown, SL1, and SL2 were p−type and SL3 was n−type.…”