GaAsBi: From Molecular Beam Epitaxy Growth to Devices

Abstract

GaAsBi has been researched as a candidate material for optoelectronic devices for around two decades. Bi-induced localized states induce a rapid rising of the valence band edge through a band anti-crossing interaction, which has a profound effect on the band gap and the spin orbit splitting. The band engineering possible, even with just a few percent bismuth, makes GaAsBi an attractive material for THz emitters, telecommunication lasers, and low noise photodetectors, among other devices. There has been substantial progress in some of these areas; however, progress towards many of the potential applications of GaAsBi has been hindered by device quality issues, brought about by the low substrate temperatures necessary for the growth of GaAsBi with sufficiently large Bi fractions. In this review, we present an overview of the applications for which GaAsBi has been advocated and the key results in these areas. We then explore the molecular beam epitaxy growth and post-growth processing of GaAsBi and the novel techniques that have been suggested to improve material quality. IntroductionReceived: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))

Understanding Growth‐Faulted GaAsBi Samples by Reflectance Anisotropy Spectroscopy

“…[4] At the same level, techniques able to characterize helpfully the grown samples are necessary, with well-defined properties: 1) a very high sensitivity to well-focused and significant properties of the chemical-physical process under examination; 2) no damage effects on the investigated samples; 3) full compatibility with the environment where the growth is carried out (ultrahigh vacuum, air, liquid); 4) suitability for in situ and real-time monitoring of growth (although also the post-growth or ex situ characterization of samples is often necessary). [5][6][7][8][9][10][11][12][13][14] In the case of GaAsBi alloys, a family of ternary alloys with extremely high potential applications in the optical fiber communication network as well as for THz applications, [15] the need of an efficient substitutional incorporation of high concentrations of Bi atoms in the As sublattice leads to the production of distortions with respect to the perfect lattice. [16,17] The more interesting and appealing properties of GaAsBi, in fact, depend on the Bi density: a large bandgap reduction of up to 90 meV/%Bi, [18] a bandgap quite temperature insensitive, [19] and a huge increase in the spin-orbit energy splitting, [20][21][22][23][24] useful in spintronic devices, as well as suppressing Auger recombination loss in near-to-mid-infrared laser diodes.…”