Impact of temperature and gamma radiation on electron diffusion length and mobility in p-type InAs/GaSb superlattices

Abstract

The minority carrier diffusion length was directly measured by the variable-temperature Electron Beam-Induced Current technique in InAs/GaSb type-II strain-layer-superlattice infrared-detector structures. The Molecular Beam Epitaxy-grown midwave infrared superlattices comprised 10 monolayers of InAs and 10 monolayers of GaSb to give a total absorber thickness of 4 lm. The diffusion length of minority electrons in the p-type absorber region of the p-type/barrier/n-type structure was found to increase from 1.08 to 2.24 lm with a thermal activation energy of 13.1 meV for temperatures ranging from 77 to 273 K. These lengths significantly exceed the individual 10-monolayer thicknesses of the InAs and GaSb, possibly indicating a low impact of interface scattering on the minority carrier diffusion length. The corresponding minority electron mobility varied from 48 to 65 cm 2 /V s. An absorbed gamma irradiation dose of 500 Gy halved the minority carrier diffusion length and increased the thermal activation energy to 18.6 meV, due to creation of radiation-induced defect recombination centers.

Temperature-Dependent Minority-Carrier Mobility inp-TypeInAs/GaSbType-II-Su

“…Considering a p-type material, experimental recombination lifetime (= 1/R(n)) data as a function of carrier density determined from the intensity-dependent TMR measurements are fitted to the total lifetime using Eqs. (4,5,10,12) as Figure 4 shows the data (circles) for representative temperatures, compared with the overall fit (solid curve). As τ Auger shows a stronger dependence on the injection level than τ rad , Auger recombination becomes dominant, and the contribution of the radiative recombination is relatively small to reliably estimate the radiative coefficient B.…”

“…Superlattice vertical transport properties are typically interrogated using vertical magneto-transport measurement [7], ultrafast all-optical time-of-flight technique [8], or electron-beam-induced microscopy method [9][10][11][12]. Among previous studies, there are few available experimental transport data on p-type T2SL photodetectors.…”

“…Transport in p-type MWIR T2SL has been also reported through the application of the quantum efficiency modeling technique [13], and as a means of investigation of the gamma irradiation effect [12].…”