Spectral blueshift and improved luminescent properties with increasing GaSb layer thickness in InAs–GaSb type-II superlattices

Abstract

We describe the photoluminescence spectroscopy (PL) and Fourier transform infrared absorbance spectroscopy characterization of a large set of InAs/GaSb type-II strained layer superlattice (SLS) samples. The samples are designed to probe the effect of GaSb layer thickness on the optical properties of the SLS, while the InAs-layer thickness is held fixed. As the GaSb layer thickness is increased, we observe a spectral blue shift of the PL peaks that is accompanied by an increase in intensity, narrower linewidths, and a large reduction in the temperature sensitivity of the luminescence. These effects occur despite a significant reduction in the electron-hole wave function overlap as the GaSb layer thickness is increased. In addition, we compare the results of empirical pseudopotential model (EPM) calculations to the observed blueshift of the primary band gap. The EPM calculations are found to be in very good agreement with the observed data.

Effect of interfaces and the spin-orbit band on the band gaps of InAs/GaSb superlattices beyond the standard envelope-function approximation

“…22 and Kaspi et al 2i grew two sets of samples with mixed IF's. Using #^=580 me V for InSblike IF's, wc use the band gap of the 6 ML/6 ML sample to fit the coupling parameter for GaAs-Iike IF's.…”

“…'s has also been calculated via the superlattice empirical pseudopotential method (SEPM). [22][23][24][25][26] Unlike the EPS-17 the SEPM (Rcf. 26) assumes that IF's remain sharp and bulklike, so that the method does not differentiate between different types of bonds possible at interfaces.…”

Study of Surface Treatments on InAs/GaSb Superlattice LWIR Detectors

“…These sidewalls are composed of InAs, GaSb, and, in part, InSb and GaAs layers. Since the thickness of InSb and GaAs layers in SLS are commonly assumed to be approximately one monolayer (ML) 10 and the thicknesses of InAs and GaSb layers are on the order of tens of MLs, formation of native oxides on GaSb and InAs is detrimental to SLS detector performance.…”

Subband transitions in dual-band n-B-n InAs/GaSb superlattice infrared photodetector identified by photoresponse spectra

“…2͑a͒ clearly exhibits two distinctive peaks that may be related to the transitions from the first heavy-and light-hole ͑HH1 and LH1͒ subbands to the conduction ͑C͒ one in the MW-SLS. [8][9][10][11][12][13] On the other hand, the PL measurement reveals a single peak that lies just at the absorption edge of each PR spectrum, which is associated with the C-HH1 emission.…”

“…6 The n-B-n InAs/ GaSb SLIP has already been proven to operate at a wavelength of about 8 m. 7 A thermal imager was also demonstrated by using ͓320ϫ 256͔ focal-plane-array SLIP with a cutoff wavelength of 4.2 m at a detector temperature of 77 K. 8 Owing to remarkable progress in the growth technology, the number of reports on the device achievement of InAs/ GaSb SLS has rapidly increased. [9][10][11][12][13] However, uncertainty still exists in understanding absorption and emission features of SLIPs because of diversity of SLS structures, 11,14 and the PR band selectivity in the dual-band n-B-n SLIP is a little ambiguous. In this letter, the subband transitions in MW-and LW-SLS are investigated by PR spectra and photoluminescence ͑PL͒ profiles.…”