Theoretical study of optoelectronic properties of GaAs 1 − x Bi x alloys using valence band anticrossing model (original) (raw)
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GaAs(1-x)Bix: A Promising Material for Optoelectronics Applications
Critical Reviews in Solid State and Materials Sciences, 2016
Bismuth alloying with GaAs has promised greater advantages in the realization of more convenient mid and near IR photonic devices owing to its novel and unique properties. The coexistence of faster band gap reduction and a strong increase in spin-orbit splitting energy with an increase in Bi concentration is one of those. However, the realization of practical devices is hindered due to several critical issues associated with the electronic properties of this material. Many of these limitations primarily arise due the difficulty obtaining high-quality structures. In this article, we review the growth and properties of GaAs (1¡x) Bi x. We have provided a comprehensive study of the properties by considering both from a fundamental perspective and also on their potential device applications.
Influence of bismuth incorporation on the valence and conduction band edges of GaAs1−xBix
Applied Physics Letters, 2008
We investigate the electronic properties of GaAs 1−x Bi x by photoluminescence at variable temperature ͑T = 10-430 K͒ and high magnetic field ͑B =0-30 T͒. In GaAs 0.981 Bi 0.019 , localized state contribution to PL is dominant up to 150 K. At T = 180 K the diamagnetic shift of the free-exciton states reveals a sizable increase in the carrier effective mass with respect to GaAs. Such an increase cannot be accounted for by an enhanced localized character of the valence band states, solely. Instead, it suggests that also the Bloch states of the conduction band are heavily affected by the presence of bismuth atoms.
Bismuth alloying in GaAs: a first-principles study
Computational Materials Science, 2008
We present a theoretical study mainly devoted to the investigation of the bowing parameter in the GaAs 1-x Bi x alloy. Results reveal that the fundamental band gap for GaAs is close to 0.08 eV and it corresponds to À2.01 eV for GaBi. The addition of Bi to GaAs serves to make the lattice constant of the crystal larger than GaAs and distorts the valence band. This causes an intrinsic asymmetry between the carrier mobility. The band gap of GaAsBi alloy decreases with increasing Bi content. Moreover, the non-linear variation of the lattice parameter is clearly visible with upward bowing parameter, equal to À0.378 ± 0.16 Å. Compared with preceding works on the matter, the band gap versus composition is well fitted with a downward bowing parameter of 1.74 ± 0.51 eV. This shows that the direct band gap of this alloy covers a spectral region ranging from near infrared to infrared.
Applied Physics Letters, 2008
We investigate the electronic properties of GaAs 1−x Bi x by photoluminescence at variable temperature ͑T = 10-430 K͒ and high magnetic field ͑B =0-30 T͒. In GaAs 0.981 Bi 0.019 , localized state contribution to PL is dominant up to 150 K. At T = 180 K the diamagnetic shift of the free-exciton states reveals a sizable increase in the carrier effective mass with respect to GaAs. Such an increase cannot be accounted for by an enhanced localized character of the valence band states, solely. Instead, it suggests that also the Bloch states of the conduction band are heavily affected by the presence of bismuth atoms.
Journal of Alloys and Compounds, 2011
Using all electron full potential -linearized augmented plane wave (FP-LAPW) method the linear and nonlinear optical susceptibilities of cubic GaAs 1−x Bi x alloys with x varying between 0.25 and 0.75 with increment of 0.25 are investigated. We have applied the generalized gradient approximation (GGA) for the exchange and correlation potential. In addition the Engel-Vosko generalized gradient approximation (EVGGA) was used. The reflectivity, refractivity, absorption coefficient and the loss function of these ternary alloys were investigated. The absorption coefficient shows that GaAs 0.25 Bi 0.75 possess the highest coefficient among the investigated alloys which supports our previous observation that the band gap decreases substantially with increasing Bi content and the materials with very small energy band gap possess the highest absorption coefficient. The investigation of the linear and nonlinear optical susceptibilities of GaAs 1−x Bi x shows a strong band gap reduction as commonly found experimentally.
Bandgap and optical absorption edge of GaAs1− xBix alloys with 0< x< 17.8%
The compositional dependence of the fundamental bandgap of pseudomorphic GaAs 1Àx Bi x layers on GaAs substrates is studied at room temperature by optical transmission and photoluminescence spectroscopies. All GaAs 1Àx Bi x films (0 x 17.8%) show direct optical bandgaps, which decrease with increasing Bi content, closely following density functional theory predictions. The smallest measured bandgap is 0.52 eV ($2.4 lm) at 17.8% Bi. Extrapolating a fit to the data, the GaAs 1Àx Bi x bandgap is predicted to reach 0 eV at 35% Bi. Below the GaAs 1Àx Bi x bandgap, exponential absorption band tails are observed with Urbach energies 3-6 times larger than that of bulk GaAs. The Urbach parameter increases with Bi content up to 5.5% Bi, and remains constant at higher concentrations. The lattice constant and Bi content of GaAs 1Àx Bi x layers (0 < x 19.4%) are studied using high resolution x-ray diffraction and Rutherford backscattering spectroscopy. The relaxed lattice constant of hypothetical zincblende GaBi is estimated to be 6.33 6 0.05 Å , from extrapolation of the Rutherford backscattering spectrometry and x-ray diffraction data.
A study on structural and electronic properties of GaAs1-xNx and GaAs1-xBix alloys
International Journal of Physical Research, 2016
We have performed first principles method to investigate structural and electronic properties of GaAs 1-x N x and GaAs 1-x Bi x ternary semiconductor alloy using Density Functional Theory and pseudo potential method within the Generalized Gradient Approximations and Local Density Approximation. The Zinc-Blende phase is found stable for GaAsN and GaAsBi alloys. In this study we investigate the both bowing parameters changing with Bismuth concentration in GaAsBi and Nitrogen concentration in GaAsN alloys. By using the bowing parameter of GaAsBi and GaAsN alloys we obtained the bandgap energies for all x concentrations (0 < x < 1) and lattice constant of both alloys which are important for wide range device application. For studied materials, lattice parameters and band gap energies are compared with available theoretical and experimental works.
Journal of Solid State Chemistry
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Compositional evolution of Bi-induced acceptor states in GaAs_{1-x}Bi_{x} alloy
Physical Review B, 2011
Far-infrared absorption measurements have been performed in nominally undoped GaAs 1−x Bi x (0.6% x 10.6%) for magnetic field up to 30 T. For 0.6% x 4.5%, the Lyman series of an acceptor has been observed. An exceedingly high value of the ground-state g factor provides strong evidence of Bi-related acceptor states. For x 5.6%, however, these acceptors suddenly disappear. Such anomalous dependence on Bi concentration parallels those recently reported in GaAs 1−x Bi x for other electronic and structural properties.
Composition dependence of photoluminescence of GaAs1−xBix alloys
Applied Physics Letters, 2009
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.