Growth of GaAs1−xBix by molecular beam epitaxy: Trade-offs in optical and structural characteristics

Abstract

Recent work has shown that Bi incorporation increases during molecular beam epitaxy (MBE) when surface processes are kinetically limited through increased growth rate. Herein we explore how the structural and optical properties of GaAs1−xBix films are modified when grown under conditions with varying degrees of kinetic limitations realized through growth temperature and growth rate changes. Within the typical window of MBE growth conditions for GaAs1−xBix, we compare films with similar (∼3%) compositions grown under conditions of reduced kinetic limitations, i.e., relatively low gallium supersaturation achieved at higher temperatures (∼350 °C) and lower growth rates (∼0.5 μm/h), to those grown farther from equilibrium, specifically, higher supersaturation achieved at lower growth temperatures (∼290 °C) and higher growth rates (∼1.4 μm/h). Both the x-ray diffraction full width at half maximum of the omega-2theta scan and the 300 K photoluminescence intensity increase when samples are grown under less kinetically limited conditions. We interpret these findings in relation to the incorporation of Bi-related microstructural defects that are more readily formed during less kinetically limited growth. These defects lead to enhanced luminescence efficiency due to the spatial localization of carriers.

Spontaneous formation of nanostructures by surface spinodal decomposition in GaAs1−xBix epilayers

“…Interestingly, investigations on LCMs in other III-V semiconductor alloys have established a correlation between the modulation wavelength K and the atom surface diffusion length k, 17,18 where K increases with increased k. In a rough approximation, K / k. 18 In the case of III-V-Bi compounds, there is a lack of data regarding atomic surface diffusion lengths, with only few works commenting on the topic. 19,20 The same is true for LCMs in bismide alloys. 11 Furthermore, it is unclear whether K is determined by k Ga , k As , or k Bi .…”

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

“…The resultant hole concentration is found to correlate with PL emission efficiency. In our previous study, 16 we found that higher growth temperature and lower growth rate can enhance PL emission efficiency, and herein, we show that these growth conditions also enhance the hole concentration.…”

“…More information on these samples can be found in our previous work. 16 Typical GaAs 1−y Bi y Raman spectra can be found in two prior studies. 9,10 Four polarized quasi-backscattering geometries can be used for the GaAs zinc blende structure:…”

“…A detailed description of growth conditions and procedure can be found elsewhere. 16 Two sets of samples were prepared and are described below. Set A is comprised of data collected across a single sample grown on 1/4 of a two-inch substrate at 320…”

Incorporation of Bi atoms in InP studied at the atomic scale by cross-sectional scanning tunneling microscopy

“…A general method for overcoming the poor solubility of Bi atoms in MBE grown III-V compounds is to grow the material at a low temperature and at a low V/Bi flux ratio [9,34,35]. Unfortunately, these growth conditions favor the formation of group-III vacancies as well as group-V related antisites or interstitials [36].…”