Intensity- and Temperature-Dependent Carrier Recombination inInAs/InAs1−xSbx

Abstract

Time-resolved measurements of carrier recombination are reported for a midwave infrared InAs=InAs 0.66 Sb 0.34 type-II superlattice (T2SL) as a function of pump intensity and sample temperature. By including the T2SL doping level in the analysis, the Shockley-Read-Hall (SRH), radiative, and Auger recombination components of the carrier lifetime are uniquely distinguished at each temperature. SRH is the limiting recombination mechanism for excess carrier densities less than the doping level (the lowinjection regime) and temperatures less than 175 K. A SRH defect energy of 95 meV, either below the T2SL conduction-band edge or above the T2SL valence-band edge, is identified. Auger recombination limits the carrier lifetimes for excess carrier densities greater than the doping level (the high-injection regime) for all temperatures tested. Additionally, at temperatures greater than 225 K, Auger recombination also limits the low-injection carrier lifetime due to the onset of the intrinsic temperature range and large intrinsic carrier densities. Radiative recombination is found to not have a significant contribution to the total lifetime for all temperatures and injection regimes, with the data implying a photon recycling factor of 15. Using the measured lifetime data, diffusion currents are calculated and compared to calculated Hg 1−x Cd x Te dark current, indicating that the T2SL can have a lower dark current with mitigation of the SRH defect states. These results illustrate the potential for InAs=InAs 1−x Sb x T2SLs as absorbers in infrared photodetectors.

Evidence of a Shockley-Read-Hall Defect State Independent of Band-Edge Energy inInAs/In(As,Sb)Type-II Superlattices

“…Samples are grown by molecular beam epitaxy using previously described techniques [6,9,10,13]. For all seven samples, the epitaxial layers consist of a GaSb buffer layer, a bottom 100-nm Al(As,Sb) barrier layer, an unintentionally doped and nominally 4-μm-thick T2SL absorber layer, a top 100-nm Al(As,Sb) barrier layer, and a 150-nm In(As,Sb) cap layer.…”

“…Temperature-and carrier-density-dependent studies on MWIR InAs=InðAs; SbÞ T2SLs have shown that SRH recombination limits the MC carrier lifetime at low temperatures and low-injection carrier densities [5,6,[8][9][10]13]. The mid-band-gap SRH recombination centers identified in MWIR InAs=InðAs; SbÞ T2SLs have been previously reported to be at an energy approximately 250 meV below the valence-band edge of bulk GaSb [5,9].…”

“…InAs=InðAs; SbÞ type-II superlattices (T2SLs) were proposed as an alternative material to Hg(Cd,Te) for infrared (IR) detection in 1985 [1]. Since then, many different designs and growth methods have been studied to improve the structural and optical properties of these T2SLs to realize next-generation IR detectors and focal plane arrays [2][3][4][5][6][7][8][9][10][11]. Improvements in detectivity and responsivity have been the main focus of T2SL photodetector development; however Hg(Cd,Te) continues to set the goals for dark current and sensitivity [12].…”

“…Improvements in detectivity and responsivity have been the main focus of T2SL photodetector development; however Hg(Cd,Te) continues to set the goals for dark current and sensitivity [12]. Improvements in T2SL detector performance depend critically on the minority-carrier (MC) lifetime, which currently is controlled by flaw-related Shockley-Read-Hall (SRH) recombination [5,6,[8][9][10]13] at typical operating temperatures. Previously, InAs=InðAs; SbÞ T2SLs have been shown to have MC lifetimes of approximately 10 μs in the midwave infrared (MWIR) [6,13] and hundreds of nanoseconds in the long-wave infrared (LWIR) [14,15], with Auger coefficients reported between 1 and 5 × 10 −26 cm 6 =s for MWIR [6,10] and low 10 −25 cm 6 =s for LWIR [15].…”

A Thermoelectrically Cooled nBn Type‐II Superlattices InAs/InAsSb/B‐AlAsSb Mid‐Wave Infrared Detector

“…This can be circumvented by Ga‐free T2SL InAs/InAsSb. The T2SL InAs/InAsSb have much longer SRH lifetimes than InAs/GaSb, but they also have much lower absorption coefficients, meaning that the dark current is improved, but quantum efficiency (QE) suffers . In this study, we examined the MWIR nBn photodetector with a T2SL InAs/InAsSb active layer with the incorporation of an AlAsSb barrier.…”