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.

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Photoluminescence ͑PL͒ has been observed from dilute InN x As 1−x epilayers grown by molecular-beam epitaxy. The PL spectra unambiguously show band gap reduction with increasing N content. The variation of the PL spectra with temperature is indicative of carrier detrapping from localized to extended states as the temperature is increased. The redshift of the free exciton PL peak with increasing N content and temperature is reproduced by the band anticrossing model, implemented via a ͑5 ϫ 5͒ k·p Hamiltonian.

The unusual N-induced band formation and band structure of Ga(N, As) and (Ga, In)(N, As) alloys are also reflected in the electronic structure of quantum wells (QWS) and device structures containing these non-amalgamation-type alloys. This review is divided into three parts. The first part deals with band structure aspects of bulk Ga(N, As) and motivates the possibility of a k•p-like parameterization of the band structure in terms of the level repulsion model between the conduction band edge of the host and a localized N-level. The second part presents experimental studies of interband transitions in Ga(N, As)/GaAs and (Ga, In)(N, As)/GaAs QW structures addressing band offsets, electron effective mass changes and an intrinsic mechanism contributing to the blueshift of the (Ga, In)(N, As) band gap on annealing. The observed interband transitions can be well described using a ten-band k•p model based on the level repulsion scheme. The third part deals with (Ga, In)(N, As)-based laser devices. The electronic structure of the active region of vertical-cavity surface-emitting laser and edge-emitter laser structures is studied by modulation spectroscopy. The gain of such structures is measured by optical methods and analysed in terms of a model combining the ten-band k•p description of the band structure and generalized Bloch equations.

Room temperature photoreflectance (PR) has been performed on three In0.32Ga0.68As/ In0.76Ga0.24As0.53P0.47 tensiley strained single-quantum-well structures, with heavy Zn modulation p-doping (5×1017 cm−3) in the quaternary barriers, which are lattice matched to an InP substrate. The PR spectra exhibit strong, well-defined, and regular Franz–Keldysh oscillations (FKO) associated with the barrier layers. We study the FKO in detail, comparing two different techniques of analyzing them to obtain a measure of the built-in electric field: (i) the conventional simple graphical asymptotic technique; and (ii) least-squares fitting to the experimental spectra using the recently proposed electromodulation model based on complex Airy functions. In the second method, the PR spectra are best described by the sum of two Airy function expressions representing degenerate heavy- and light-hole band edges. Good fits are obtained without the need to use an empirical energy-dependent broadening term to account for the effects of nonflatband modulation and nonuniform fields. The results are consistent with FKO originating from heavy- and light-hole transitions under the same electric field, but having a partial destructive interference effect in the PR spectrum. The fitted field value of ∼17 kV/cm is essentially the same as that obtained in the graphical analysis which assumed that the FKO were heavy-hole dominated. However, contrary to previous suggestions, neither the heavy- nor light-hole contributions dominate the actual FKO spectrum.