GaAsPBi epitaxial layer grown by molecular beam epitaxy

Abstract

GaAsPBi is a new class of quaternary III-V compounds that extends the concept of band gap engineering on GaAs with potentials for lattice matching and excellent temperature stability. The alloy has so far been grown only by metalorganic vapor phase epitaxy and this work represents the first epitaxial results of the alloy grown by molecular beam epitaxy (MBE), an alternative technique and better suited for low-temperature processes involving Bismuth. Crystalline quality of the alloys is probed by high-resolution x-ray diffraction and photoluminescence (PL) which show that smooth and optically active films can be grown in limited parameter windows. Temperature-dependent PL shows that the 200 nm, MBE-grown GaAs 0.38 P 0.44 Bi 0.18 film (the composition estimated using x-ray photoelectron spectroscopy) has a band gap temperature stability close to that of GaAsBi, and superior to GaAs. The role of Bi in the quaternary alloy is complicated: Bi not only gets incorporated into the growing film but also enhances the P molar fraction. Based on this insight, strategies for growing GaAsPBi epilayers which are lattice-matched to GaAs are described, potentially affecting many important III-V based heterostructures such as lasers, light-emitting diodes, and solar cells.

GaAs/GaAsPBi core–shell nanowires grown by molecular beam epitaxy

“…We note all the EDS acquisition spectra for CS3 have lower P content than those for CS4 despite the identical BEP P2 because of the catalytic effect of the Bi atoms towards the existing P atoms. The effect was reported earlier in the planar case [30].…”

“…Thus the compositional estimation from optical results can only be made for homogeneous materials (e.g. in the planar cases [30,31]).…”

“…For GaAsBi thinfilms, Jacobson et al [27] suggested that, in theory, the Bi incorporation becomes more favorable under a tensile film. This stress configuration enhances the incorporation of Bi into the III-V-Bi matrix and has been applied for the growths using metalorganic vapor phase epitaxy (MOVPE) [28,29] and molecular beam epitaxy (MBE) [30,31] techniques. Besides, the quaternary alloy GaAsPBi grown lattice-matched on GaAs (001) was experimentally demonstrated, thus there is no accumulated strain in this heterostructure [31].…”

Optical properties of lattice-matched GaAsPBi multiple quantum wells grown on GaAs (001)

“…BEP As4 was sufficiently provided for each growth to avoid the formation of metallic droplets. We note that the BEP V :BEP III value earlier proposed [24] cannot be fully exploited because of the different ionization energies between P 2 and As 4 , however, the proposed BEP V :BEP III value was adopted as the minimal value for this work. An optimal BEP V :BEP III value increases consistently with a higher designed As content (lower designed P content).…”

“…Nattermann et al [22] showed that the saturated Bi incorporation level is shifted higher for the Ga(NAsBi) and Ga(PAsBi) quaternary alloys compared to Ga(AsBi) ternary alloy. This technique, as demonstrated by metal-organic vapor phase epitaxy (MOVPE) [21][22][23] and molecular beam epitaxy (MBE) [24], also provides an opportunity to grow Bi-containing epitaxial layers lattice-matched to GaAs substrate.…”