Growth and Optical Properties of Ga[sub.2]O[sub.3] Layers of Different Crystalline Modifications

• Published in: Coatings (Basel) Vol. 12; no. 12
• Main Authors: Osipov, Andrey V, Sharofidinov, Shukrillo Sh, Osipova, Elena V, Kandakov, Andrey V, Ivanov, Andrey Y, Kukushkin, Sergey A
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.11.2022
• Subjects: Analysis; Optical properties; Raman spectroscopy; Silicon carbide; Russia
• ISSN: 2079-6412; 2079-6412
• DOI: 10.3390/coatings12121802

In the present work, a new method of growing layers of three main crystal modifications of Ga[sub.2]O[sub.3], namely α-phase, ε-phase, and β-phase, with thickness of 1 µm or more was developed. The method is based on the use of two approaches, namely a combination of Ga[sub.2]O[sub.3] growth using the hydride vapor-phase epitaxy (HVPE) method and the use of a silicon crystal with a buffer layer of dislocation-free silicon carbide as a substrate. As a result, Ga[sub.2]O[sub.3] gallium oxide layers of three major Ga[sub.2]O[sub.3] crystal modifications were grown, namely, α-phase, ε-phase, and β-phase. The substrate temperatures and precursor flux values at which it is possible to grow only α-phase, only ε-phase, or only β-phase without a mixture of these phases were established. It was found that the metastable α- and ε-phases change into the stable β-phase when heated above 900 °C. Experimentally obtained Raman and ellipsometric spectra of α-phase, ε-phase, and β-phase of Ga[sub.2]O[sub.3] are presented. The theoretical study of the Raman spectra and the dependences of dielectric function on photon energy for all three phases was carried out. The vibrations of Ga[sub.2]O[sub.3] atoms corresponding to the main lines of the Raman spectrum of the α-phase, ε-phase, and β-phase were simulated by density functional methods.