Intermixing studies in GaN_1−xSb_x highly mismatched alloys

Abstract

GaN1−xSbx with x~ 5-7% is a highly mismatched alloy predicted to have favorable properties for application as an electrode in a photo-electrochemical cell for solar water splitting. In this study, we grew GaN1−xSbx under conditions intended to induce phase segregation. Prior experiments with the similar alloy GaN1−xAsx, the tendency of Sb to surfact, and the low growth temperatures needed to incorporate Sb, all suggested that GaN1−xSbx alloys would likely exhibit phase segregation. We found that, except for very high Sb compositions, this was not the case, and that instead interdiffusion dominated. Characteristics measured by optical absorption were similar to intentionally grown bulk alloys for the same composition. Furthermore, the alloys produced by this method maintained crystallinity for very high Sb compositions, and allowed higher overall Sb compositions. This method may allow higher temperature growth while still achieving needed Sb compositions for solar water splitting applications.

Electronic band structure of highly mismatched GaN1−xSbx alloys in a broad composition range

“…More details of the crystal growth and structural characterization will be presented elsewhere. 24 The optical properties of the films were studied by optical transmission and reflection in the spectral range of 250-2500 nm using a Perkin Elmer Lambda 950 Spectrophotometer. Figure 1 illustrates the measured absorption spectra for five of the eight GaN 1Àx Sb x thin films with compositions ranging from x ¼ 0 to 0.42.…”

Undoped p-type GaN1–xSbx alloys: Effects of annealing

“…Two sets of GaN 1-x Sb x thin films are studied in this letter. The first set consists of the previously reported films 14,20 grown by multilayer intermixing at a constant temperature of 325 C with an Sb composition x up to 0.30 along 0003-6951/2016/109(25)/252102/5/$30.00…”

“…Transmission electron microscopy (TEM) measurements performed on selected samples of the first set were reported in Ref. 20. The TEM results showed that GaN grown without Sb is polycrystalline with grains primarily consisting of 2H GaN with the (0002) planes aligned with the (0006) sapphire substrate planes.…”