GaAs1−yBiy Raman signatures: illuminating relationships between the electrical and optical properties of GaAs1−yBiy and Bi incorporation

Abstract

We report the use of two Raman signatures, the Bi-induced longitudinal-optical-plasmon-coupled (LOPC) mode and the GaAs Fröhlich scattering intensity, present in nominally undoped (100) GaAs1−yBiy to predict the 300K photoluminescence intensity and Bi composition (y) in GaAs1−yBiy. The LOPC mode is used to calculate the hole concentration in GaAs1−yBiy epitaxial layers. A linear relationship between hole concentration and photoluminescence intensity is found for a range of samples grown at various temperatures and growth rates. In addition, the composition (y) of Bi in GaAs1−yBiy is also found to be linearly related to the GaAs Fröhlich scattering intensity.

Structural and optical properties of n-type and p-type GaAs(1−x)Bi x thin films grown by molecular beam epitaxy on (311)B GaAs substrates

“…Similar behavior was reported previously in the literature for undoped (100) and (311)B GaAs(1−x)Bix samples [13,29,34,36,39,40,59]. Taking LO() of bulk GaAs crystal at 292 cm -1 as reference, the experimental value obtained for the ratio /Bi% for LO() GaAs mode, -86.5 (n-type) and -70.4 (p-type), and TO() GaAs mode, -26.6 (n-type) and -25.9 (p-type), are consistent with values obtained in literature, i.e., -68 to -120 and -20 to -30, respectively [13,30,35,37,41]. It is well known that the crystal structure is affected by the incorporation of Bi atom, which substitutes an As atom and, therefore, introduces strain and crystal disorder [13,29,34,36,37,[39][40][41]59].…”

“…For backscattering Raman configuration of (311)B face, both Raman LO () and TO () modes are allowed by selection rules. The observed Bi related Raman peaks, around 181, 210, and 226 cm -1 , were previously reported in the literature [13,29,[34][35][36][37][38][39][40][41][42][43]. However, the interpretation of these peaks is controversial [37,[40][41][42][43].…”

“…The observation of similar linewidth of LO () peaks for n-GaAs0.94Bi0.06 as compared to n-GaAs or p-GaAs, indicates a compensation effect of ndoping with the intrinsic p-doping due to Bi incorporation in GaAs [37]. The LOCP for undoped GaAs(1−x)Bix samples is due to hole plasmons, which usually contribute to the changes observed in the Raman spectra, particularly for x > 1% [13,35,40,41,59]. However, the observed differences between n-GaAs0.94Bi0.06 and p-GaAs0.94Bi0.06 samples are not related to Bi concentrations which are 5.4% for both samples, or to the effect of strain, also the same for the two samples, as the XRD results indicate.…”

Surface effects of vapour-liquid-solid driven Bi surface droplets formed during molecular-beam-epitaxy of GaAsBi

“…PL signals have been detected from deep below the surface, even through a relatively thick GaAs 1− x Bi x epilayers (>300 nm); detecting the efficiently laminating GaAs substrate from GaAs 1− x Bi x /GaAs structures is a common feature for PL studies of these films4169. There are two main reasons for this: (i) photons emitted from the material as luminescence will possess longer wavelengths (lower energy) than the excitation wavelength, and will be able to escape from a larger depth ( α out << α in ), and (ii) the excited charge carriers may diffuse deeper into the material and recombine (emitting PL) a further distance away from where they were excited.…”

Polarization dependent photoluminescence and optical anisotropy in CuPtB-ordered dilute GaAs1–xBix alloys

“…The width of PL peaks seen here is typical for GaAsBi alloys and reflects Bi-induced localized states near the band edge. [26][27][28] The PL intensity of GaAsBi with increasing Bi concentration tends to be weaker and PL spectra become noisier. This is also evident in the non-uniform lattice of S6 composed of APDs.…”