Characterization of AlInAsSb and AlGaInAsSb MBE-grown Digital Alloys

Abstract

As one of the few Type I band offset, antimony-based material systems available for 3.3 to 4.2 micron mid-infrared multiple quantum well lasers, AlInAsSb alloys have been used as barriers with InAsSb wells. Previously, AlxIn(1-x)AsySb(1-y) quaternary alloys have been grown by MBE as random alloys up to an aluminum fraction, x = 0.10 on GaSb substrates and x = 0.15 on InAs substrates. Random alloy growth of quaternary films with increased aluminum content, although beneficial to the devices, is limited by a miscibility gap. We have used a digital alloy technique to grow stable, single phase, GaSb lattice-matched, optically smooth quaternary alloys for aluminum fractions of 0.05 to 0.5, well into the miscibility gap. DCXRD results show FWHM of 0th order alloy peaks are within 1.5 to 2 times that of the highly crystalline GaSb substrates and have well defined thickness fringes corresponding to the total film thickness and the digital alloy period. TEM images show very well ordered alloys with characteristic ultrathin superlattice structure having smooth interfaces, very little strain and atomic ordering limited to that imposed by the digital alloy technique. Photoluminescence measurements are used to fit a model for bandgap prediction from known alloy compositions. Theoretical studies have predicted that the addition of a fifth element, gallium, may help suppress Auger recombination through its effects on the subband structure. So, gallium is added to the quaternary to produce a quinternary alloy lattice-matched to GaSb. These AlGaInAsSb alloys have DCXRD and TEM results similar to the quaternary. The stable, single-phase growth of these quinternary alloys across the composition range is promising for improving the operating characteristics of mid-IR lasers.

Low-noise AlInAsSb avalanche photodiode

“…V C 2016 AIP Publishing LLC 108, 081102-1 of the resulting Al x In 1Àx As y Sb 1Ày digital alloy films are provided elsewhere. [18][19][20] A cross-sectional schematic of the Al 0.7 In 0.3 As 0.3 Sb 0.7 device is shown in Fig. 1.…”

Broadly Tunable AlInAsSb Digital Alloys Grown on GaSb

“…Zederbauer et al have improved AlInAsSb random alloy growth on InAs, which exhibits similar challenges to growth on GaSb. Most pertinent to the work described here, though, Vaughn et al have recently shown that stable AlInAsSb can be grown well within the miscibility gap by molecular beam epitaxy (MBE) as a digital alloy of the component binaries, AlAs, AlSb, InAs, and InSb. − Using this approach, mid-IR InAsSb/AlInAsSb type-I diode lasers have previously been demonstrated. , However, these previous studies were limited to Al fractions ranging from 0% to 40%, and photoluminescence (PL) was only observed up to Al fractions of 30%. In this letter, we report on the growth and optoelectronic properties of AlInAsSb digital alloys with Al fractions ranging from 0% to 80%; we identify the functional dependence of the direct bandgap and band offsets on the Al fraction, as well as a probable transition from direct-gap to indirect-gap at an Al fraction of ∼72%.…”

Toward deterministic construction of low noise avalanche photodetector materials

“…Specifically, the increased understanding of surfactant mediated growth, the effect of growth temperature, and the ability to control material deposition on the sub-monolayer scale have allowed for high-quality digital alloy growth. [43][44][45] These advances suggest the potential for deterministically designing APD materials on the few atom scale, the results of which will be discussed later in this paper.…”