Bi-induced band gap reduction in epitaxial InSbBi alloys

Abstract

The properties of molecular beam epitaxy-grown InSb1−xBix alloys are investigated. Rutherford backscattering spectrometry shows that the Bi content increases from 0.6% for growth at 350 °C to 2.4% at 200 °C. X-ray diffraction indicates Bi-induced lattice dilation and suggests a zinc-blende InBi lattice parameter of 6.626 Å. Scanning electron microscopy reveals surface InSbBi nanostructures on the InSbBi films for the lowest growth temperatures, Bi droplets at intermediate temperatures, and smooth surfaces for the highest temperature. The room temperature optical absorption edge was found to change from 172 meV (7.2 μm) for InSb to ∼88 meV (14.1 μm) for InSb0.976Bi0.024, a reduction of ∼35 meV/%Bi.

Novel Dilute Bismide, Epitaxy, Physical Properties and Device Application

“…However, recent reports for the MBE grown InSbBi and InAsBi showed very different bandgap narrowing rate. Svensson et al obtained a narrowing rate of 38 meV/% for InAsBi by 77 K PL method [164] whereas the RT absorption by Rajpalke et al gave a narrowing rate of about 35 meV/% for InSbBi [180], about twice as that in Reference [20]. In a report of Feng et al [150], they investigated the thermal annealing influence on optical band edge for GaNAsBi.…”

“…Use of a low temperature is found to favor the Bi incorporation. A maximum Bi content of 5% is achieved when grown at 250 • C. Song et al [179] have grown InSbBi films on GaAs substrate using MBE and achieved 2% Bi [180] incorporation. Secondary ion mass spectroscopy (SIMS) measurements demonstrate a high In component in GaSb region and a high Ga component in InSb region as a result of In-Ga intermixing induced by Bi.…”

“…In some reports on the spectral investigation of dilute bismides [180,217,239,240], the spectral lineshape broadens as Bi content increases at the low-content region, for either absorption, PL or PR measurements. The inhomogeneous distribution of Bi atoms [241] and the Bi pairs/clusters-related acceptor levels near the VBM [67,221] are the dominant reasons for the spectral broadening in thin-film bismides.…”

Band gap reduction in InNxSb1-x alloys: Optical absorption, k · P modeling, and density functional theory

“…This is a consequence of the N level lying more than 550 meV above the CBM in InNSb compared with only 250 meV for GaNAs. The InNSb band gap reduction per %N is greater than twice that observed per %Bi in InSbBi alloys (35 meV%Bi), 53 but is accompanied by much greater lattice parameter change due to the greater difference between the zinc blende InN and InSb lattice parameters compared with that of the zinc blende InBi and InSb parameters. Additionally, the InNSb calculation suggests that at room temperature band gap closure will occur for x > 2.3%, giving a semimetallic band structure.…”

Enhancement of Rashba interaction in GaAs/AlGaAs quantum wells due to the incorporation of bismuth

“…Following the experimental verification of the findings reported in this study it will be necessary to look to the indium based ternary alloys InSbBi and InAsBi, which have an increased spin-orbit interaction and reduced bandgap [24][25][26][27] . Due to their strong potential for long wavelength (8 − 14µm) detection there has been significant interest in these alloys.…”