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The bandgap energy of the dilute bismuth GaBixSb1−x alloy depending on temperature

Zhao Chuan-Zhen, Qi Xue-Lian

Materials Science Poland

2021

Vol. 39, No. 3

298--304

The bandgap energy of the dilute bismuth GaBixSb1−x alloy vs. temperature is investigated in this study. Its reduced temperature-sensitiveness is because of the localized character of the valence band states (VBS). In order to describe the reduced temperature-sensitiveness of the bandgap energy, a new term including localized energy is added to Varshni's equation. It is found that the localized energy exhibits an increasing trend as the bismuth fraction increases, which indicates that the localized character of the VBS becomes strong with the increasing bismuth fraction. It is also found that the influence of the bismuth fraction on the temperature dependence of the bandgap energy of GaBixSb1−x is smaller than that of GaBixSb1−x. In addition, the element indium is undoubtedly a good candidate to lessen the bismuth fraction to realize that the spin-orbit-splitting (SOP) energy surpasses the bandgap energy in GaBixSb1−x.

Metal-organic chemical vapour deposition of lithium manganese oxide thin films via single solid source precursor

Oyedotun K. O., Ajenifuja E., Olofinjana B., Taleatu B. A., Omotoso E., Eleruja M. A., Ajayi E. O. B.

Materials Science Poland

2015

Vol. 33, No. 4

725--731

Lithium manganese oxide thin films were deposited on sodalime glass substrates by metal organic chemical vapour deposition (MOCVD) technique. The films were prepared by pyrolysis of lithium manganese acetylacetonate precursor at a temperature of 420 degrees C with a flow rate of 2.5 dm3/min for two-hour deposition period. Rutherford backscattering spectroscopy (RBS), UV-Vis spectrophotometry, X-ray diffraction (XRD) spectroscopy, atomic force microscopy (AFM) and van der Pauw four point probe method were used for characterizations of the film samples. RBS studies of the films revealed fair thickness of 1112.311 (1015 atoms/cm2) and effective stoichiometric relationship of Li0.47Mn0.27O0.26. The films exhibited relatively high transmission (50 % T) in the visible and NIR range, with the bandgap energy of 2.55 eV. Broad and diffused X-ray diffraction patterns obtained showed that the film was amorphous in nature, while microstructural studies indicated dense and uniformly distributed layer across the substrate. Resistivity value of 4.9 Omega.cm was obtained for the thin film. Compared with Mn0.2O0.8thin film, a significant lattice absorption edge shift was observed in the Li0.47Mn0.27O0.26film.

Modification of energy bandgap in lattice mismatched InGaAs/GaAs heterostructures

Gelczuk Ł., Dąbrowska-Szata

Optica Applicata

2009

Vol. 39, nr 4

845-852

This paper addresses some physical aspects and presents experimental results concerning to phenomena which evoke modification of band structure in lattice mismatched InGaAs/GaAs heterostructures, namely the introduction of extra deep-lying energy levels in the bandgap. The deep level transient spectroscopy reveals commonly observed deep level defects in GaAs-based structures associated with native point defects as well as misfit dislocations related to strain relaxation processes.