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

The incorporation of bismuth (Bi) in GaAs results in a large reduction of the band gap energy (E g ) accompanied with a large increase in the spin-orbit splitting energy ( SO ), leading to the condition that SO > E g , which is anticipated to reduce hot-hole producing Auger recombination losses whereby the energy and momentum of a recombining electron-hole pair are given to a second hole which is excited into the spin-orbit band. We theoretically investigate the electronic structure of experimentally grown GaBi x As 1−x samples on (100) GaAs substrates by directly comparing our data with room temperature photomodulated reflectance (PR) measurements. Our atomistic theoretical calculations, in agreement with the PR measurements, confirm that E g is equal to SO for x ≈ 9%. We then theoretically probe the inhomogeneous broadening of the interband transition energies as a function of the alloy disorder. The broadening associated with spin-split-off transitions arises from conventional alloy effects, while the behavior of the heavy-hole transitions can be well described using a valence bandanticrossing model. We show that for the samples containing 8.5% and 10.4% Bi the difficulty in identifying a clear light-hole-related transition energy from the measured PR data is due to the significant broadening of the host matrix light-hole states as a result of the presence of a large number of Bi resonant states in the same energy range and disorder in the alloy. We further provide quantitative estimates of the impact of supercell size and the assumed random distribution of Bi atoms on the interband transition energies in GaBi x As 1−x . Our calculations support a type-I band alignment at the GaBi x As 1−x /GaAs interface, consistent with recent experimental findings.

The Ga(AsBi) material system opens opportunities in the field of high efficiency infrared laser diodes. We report on the growth, structural investigations, and lasing properties of dilute bismide Ga(AsBi)/(AlGa)As single quantum well lasers with 2.2% Bi grown by metal organic vapor phase epitaxy on GaAs (001) substrates. Electrically injected laser operation at room temperature is achieved with a threshold current density of 1.56 kA/cm2 at an emission wavelength of ∼947 nm. These results from broad area devices show great promise for developing efficient IR laser diodes based on this emerging materials system.

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