Electronic structure of C2N2X (X=O, NH, CH2): Wide band gap semiconductors J. Appl. Phys. 112, 013537 (2012) In-plane mapping of buried InGaAs quantum rings and hybridization effects on the electronic structure J. Appl. Phys. 112, 014319 (2012) Incorporation, valence state, and electronic structure of Mn and Cr in bulk single crystal β-Ga2O3 J. Appl. Phys. 111, 123716 (2012) Determination of conduction band offset between strained CdSe and ZnSe layers using deep level transient spectroscopy Appl. Phys. Lett. 100, 252110 (2012) Electronic structure and linear magnetoresistance of the gapless topological insulator PtLuSb Appl. Phys. Lett. 100, 252109 (2012) Additional information on J. Appl. Phys. The GaBi x As 1Àx bismide III-V semiconductor system remains a relatively underexplored alloy particularly with regards to its detailed electronic band structure. Of particular importance to understanding the physics of this system is how the bandgap energy E g and spin-orbit splitting energy D o vary relative to one another as a function of Bi content, since in this alloy it becomes possible for D o to exceed E g for higher Bi fractions, which occurrence would have important implications for minimising non-radiative Auger recombination losses in such structures. However, this situation had not so far been realised in this system. Here, we study a set of epitaxial layers of GaBi x As 1Àx (2.3% x 10.4%), of thickness 30-40 nm, grown compressively strained onto GaAs (100) substrates. Using room temperature photomodulated reflectance, we observe a reduction in E g , together with an increase in D o , with increasing Bi content. In these strained samples, it is found that the transition energy between the conduction and heavy-hole valence band edges is equal with that between the heavy-hole and spin-orbit split-off valence band edges at $9.0 6 0.2% Bi. Furthermore, we observe that the strained valence band heavy-hole/light-hole splitting increases with Bi fraction at a rate of $15 (61) meV/Bi%, from which we are able to deduce the shear deformation potential. By application of an iterative strain theory, we decouple the strain effects from our experimental measurements and deduce E g and D o of free standing GaBiAs; we find that D o indeed does come into resonance with E g at $10.5 6 0.2% Bi. We also conclude that the conduction/valence band alignment of dilute-Bi GaBiAs on GaAs is most likely to be type-I. V C 2012 American Institute of Physics. [http://dx

We describe how the Bi content of GaAs 1−x Bi x epilayers grown on GaAs can be controlled by the growth conditions in molecular beam epitaxy. Nonstandard growth conditions are required because of the strong tendency for Bi to surface segregate under usual growth conditions for GaAs. A maximum Bi content of 10% is achieved at low substrate temperature and low arsenic pressure, as inferred from x-ray diffraction measurements. A model for bismuth incorporation is proposed that fits a large body of experimental data on Bi content for a wide range of growth conditions. Low growth rates are found to facilitate the growth of bismide alloys with a low density of Bi droplets.

Room temperature photoluminescence ͑PL͒ spectra have been measured for GaAs 1−x Bi x alloys with Bi concentrations in the 0.2%-10.6% range. The decrease in the PL peak energy with increasing Bi concentration follows the reduction in bandgap computed from density functional theory. The PL peak energy is found to increase with PL pump intensity, which we attribute to the presence of shallow localized states associated with Bi clusters near the top of the valence band. The PL intensity is found to increase with Bi concentration at low Bi concentrations, peaking at 4.5% Bi.

The photoluminescence from a Ga͑AsBi͒ sample is investigated as a function of pump power and lattice temperature. The disorder-related features are analyzed using a Monte Carlo simulation technique. A two-scale approach is introduced to separately account for cluster localization and alloy disorder effects. The corresponding characteristic energy scales of 11 and 45 meV are deduced from the detailed comparison between experiment and simulation.

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