Double-Band Anticrossing in GaAsSbN Induced by Nitrogen and Antimony Incorporation

Photoreflectance spectroscopy is utilized to study the effect of dilute nitrogen and antimony on the electronic band structure of as-grown GaAs 1-x-y Sb x N y alloys, which are potential materials for 1 eV solar cells and long-wavelength optoelectronic devices. The band gap, spin--orbit splitting, a...

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Published inApplied physics express Vol. 6; no. 12; pp. 121202 - 121202-4
Main Authors Lin, Kuang-I, Lin, Kuo-Lung, Wang, Bo-Wei, Lin, Hao-Hsiung, Hwang, Jenn-Shyong
Format Journal Article
LanguageEnglish
Published The Japan Society of Applied Physics 01.12.2013
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Summary:Photoreflectance spectroscopy is utilized to study the effect of dilute nitrogen and antimony on the electronic band structure of as-grown GaAs 1-x-y Sb x N y alloys, which are potential materials for 1 eV solar cells and long-wavelength optoelectronic devices. The band gap, spin--orbit splitting, and valence-band maximum to the N-induced upward conduction-band transition, for the first time, are obtained and analyzed using the double-band anticrossing model. The $E_{\text{N}}$ level with respect to the GaAs valence-band maximum and the interaction potential are determined as 1.540 and 2.839 eV, respectively. The results are helpful information for intermediate-band solar cell application.
Bibliography:(a) PR spectra of the GaAs 1-x-y Sb x N y alloys at 298 K pumped with a He--Ne laser operating at 633 nm. The numbers show the index of the $n$th extreme of FKOs. The lowest spectrum is enlarged three times. (b) Schematic diagram showing the relative positions of the energy levels at $\Gamma$ point of GaAsSbN explained using the DBAC model. (c) Plot of FKO extreme, $E'_{n}$ vs $F_{n}$ for the GaAsSbN alloys. The intercepts indicate the band gaps of the alloys. The inset shows the high-resolution X-ray rocking curve of the GaAs 0.932 Sb 0.051 N 0.017 /GaAs heterostructure, whose lattice mismatch of $-9.2\times 10^{-4}$ is larger than those of the other two samples. PR spectra of the GaAs 1-x-y Sb x N y alloys at 298 K pumped with a He--Cd laser operating at 325 nm. The spectra with energy below 1.25 eV are detected using an InGaAs photodiode and that above 1.25 eV are detected using a Si photodiode. The red lines represent theoretical fits using Eq. ( ). The band gap ($E_{0}$), the Sb-affected spin--orbit band to the conduction band minimum ($E_{0}+\Delta_{0}$), and the valence band maximum to the N-induced upward conduction band ($E_{+}$) are observed. Transition energies versus N and Sb composition. The solid symbols depict the transition energies of GaAs 1-x-y Sb x N y alloys obtained from PR spectra. The open symbols represent the calculated transition energies of GaAs 1-x Sb x alloys using the VCA and VBAC model. The colored symbols are projections of the transition energies on the energy--N Composition plane. Projections of the transition energies (symbols) as illustrated in Fig. . The solid lines are the least-squares fits to the CBAC model based on the energy levels of GaAs 1-x Sb x alloys considering the VCA and VBAC model. The dotted lines are produced using the obtained CBAC parameters, i.e., $E_{\text{N}}$ and $C_{\text{N}}$.
ISSN:1882-0778
1882-0786
DOI:10.7567/APEX.6.121202