Band gap of InAs1−xSbxwith native lattice constant

Abstract

The bandgap energy of the alloy InAsSb has been studied as function of composition with special emphasis on minimization of strain-induced artifacts. The films were grown by molecular beam epitaxy on GaSb substrates with compositionally graded buffer layers that were designed to produce strain-free films. The compositions were precisely determined by high-resolution x-ray diffraction. Evidence for weak, long-range, group-V ordering was detected in materials exhibiting residual strain and relaxation. In contrast, unstrained films having the nondistorted cubic form showed no evidence of group-V ordering. The photoluminescence (PL) peak positions therefore corresponds to the inherent bandgap of unstrained, unrelaxed, InAsSb. PL peaks were recorded for compositions up to 46% Sb, reaching a peak wavelength of 10.3 μm, observed under low excitation at T=13K. The alloy bandgap energies determined from PL maxima are described with a bowing parameter of 0.87 eV, which is significantly larger than measured for InAsSb in earlier work. The sufficiently large bowing parameter and the ability to grow the alloys without ordering allows direct bandgap InAsSb to be a candidate material for low-temperature long-wavelength infrared detector applications.

Гетероэпитаксиальные структуры InAs-=SUB=-1-x-=/SUB=-Sb-=SUB=-x-=/SUB=- на градиентных буферных слоях GaInSb и AlGaInSb

“…где подгоночный параметр C = 0.67−0.87 эВ зависит от структурного совершенства образцов и температуры [4]. В технологии получения высококачественных тонких пленок, свободных от внутренних напряжений и дисло-каций, важную роль играет выбор подложки, на которой будет происходить рост пленки.…”

Development of Bulk InAsSb Alloys and Barrier Heterostructures for Long-Wave Infrared Detectors

“…Electron diffraction patterns of unstrained InAsSb alloys showed a random (ordering-free) distribution of group V elements. 8 Thus, the observed energy gaps of the alloys are inherent, and were not due to CuPttype ordering or residual strain effects. In InAsSb alloys with 40% Sb at T = 77 K, the background electron concentrations were as low as 1.5 9 10 15 cm À3 .…”

“…1b) was obtained for a bowing parameter of 0.87 eV. 8,20 The absorption spectrum for InAsSb with a 50% Sb composition ( Fig. 2) was obtained from the transparency spectra of the heterostructure and from the same wafer with the epilayer polished off.…”

“…Electron diffraction patterns showed no evidence of long-range CuPt-type ordering. 8 PL spectra were measured with a Fourier-transform infrared (FTIR) spectrometer equipped with a HgCdTe detector with a 14 lm cutoff wavelength. The PL was excited by a 1064-nm solid-state laser with a power of 100 mW.…”

“…6 Recently, the authors of this paper developed bulk InAsSb alloys with Sb compositions up to 46%, grown unrelaxed with low residual strain on compositionally graded GaInSb and AlInSb buffers on GaSb substrates. 7,8 InAsSb alloys with 40% Sb showed the photoluminescence (PL) maximum at an energy of 0.12 eV.…”