Electronic structure and optical properties of Sn2x Ga2(1−x)O3 compounds

Abstract

Band structure, density of states, electron density difference, and optical properties of intrinsic -Ga 2 O 3 and Sn 2x Ga 2(1x) O 3 (x= 3.125%-6.25%) compounds are studied using first-principle calculations based on the density functional theory. The anisotropic optical properties are investigated by means of the complex dielectric function, which are explained by the selection rule of band-to-band transitions. All the calculation results indicate that the conductivity of Sn 2x Ga 2(1x) O 3 is super to -Ga 2 O 3 , and the calculated results consist with experiments that have been reported. electronic structure, optical properties, -Ga 2 O 3 , Sn 2x Ga 2(1x) O 3 compounds PACS: 71.20.Nr, 78.20.Ci, 81.05.Je, 71.15.Ap, 71.15.Mb -Ga 2 O 3 is an important wide band gap (4.2-4.9 eV) semi-conductor. It has high transmittance from visible to deep ultraviolet (UV) region and has high thermal stability, making it a very promising candidate for the optoelectronic devices operating at short wavelengths. The deep ultraviolet transparent conductive oxide (TCO) films have recently emerged for the uses such as antistatic electric layers of phase shift masks for photolithograph, dielectric films on GaAs substrates in metal oxide semiconductor field effect transistors [1], field effect devices [2], high-temperature gas sensors [3], and transparent electrodes for UV optoelectronic devices [4]. The refractive index value (1.8-1.9) of such films is close to the square root of most III-V semiconductors, which makes it an ideal single layer anti-reflection coating for III-V semiconductors [5]. For this purpose new TCO materials need to be explored. Creating deep-UV transparent conductive films encounters several difficulties. So the interest in its electronic and optical properties has increased because of its potential application as an ultraviolet transparent conducting oxide [6][7][8][9][10]. But the conductivity of the intrinsic -Ga 2 O 3 is too poor to meet the requirements of applications. Thus selecting the appropriate doping elements to improve the electrical conductivity is very important in this regard. Tetravalent tin ion was chosen as the dopant, for the ionic radius of Sn +4 is close to Ga +3 , and the Sn +4 ion prefers six fold coordination, and tends to substitute Ga +3 octahedral sites. Thus, we can expect that the introduction of Sn will result in the formation of shallow donor levels and oxygen vacancies in films. Many experimental studies have been carried out to explore the electronic and optical properties of the Sn 2x Ga 2(1x) O 3 compounds. Masahiro Orita [9] prepared Sn 2x Ga 2(1x) O 3 thin films using pulsed laser deposition method, and electrical conductivity of 8.2 S cm 1 was obtained. Sn 2x Ga 2(1x) O 3 single crystal with (100) plane was grown using floating zone method by Shigeo Ohira [11]. The crystal had a n-type conductivity and a resistivity of 7.92×10 −2  cm. Experimental studies indicate that the Sn 2x Ga 2(1x) O 3 compound is a deep ultraviolet transparent conducting oxide, but so far...

Exact Solution of the Gyration Radius of an Individual's Trajectory for a Simplified Human Regular Mobility Model

“…It is obvious that all the distributions are different: they peak respectively at 2𝑐. A recent empirical research [21] has indicated that most of urban human individuals have peaked travel distance distributions, peaking at the distance between his or her two most visited locations, coinciding with our model results. These results suggest that although the empirical evidence in Ref.…”

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