Influence of Carrier Gases on the Quality of Epitaxial Corundum-Structured α-Ga2O3 Films Grown by Mist Chemical Vapor Deposition Method

Abstract

This report systematically investigates the influence of different carrier gases (O2, N2, and air) on the growth of gallium oxide (Ga2O3) thin films on c-plane sapphire substrates by using the mist-CVD method. Although XRD and Raman measurements show that the pure corundum-structured α-Ga2O3 with single (0006) plane orientation was successfully obtained for all three different carrier gases, the crystal quality could be greatly affected by the carrier gas. When O2 is used as the carrier gas, the smallest full-width at half maximum (FWHM), the very sharp absorption cutoff edge, the perfect lattice structure, the highest growth rate, and the smooth surface can be obtained for the epitaxial α-Ga2O3 film as demonstrated by XRD, UV-VIS, TEM, AFM (Atomic Force Microscope), and SEM measurements. It is proposed that the oxygen content in carrier gas should be responsible for all of these results. XPS (X-ray photoelectron spectroscopy) analysis also confirms that more oxygen elements can be included in epitaxial film when O2 is used as the carrier gas and thus help improve the crystal quality. The proper carrier gas is essential for the high quality α-Ga2O3 growth.

The Effect of Gate Work Function and Electrode Gap on Wide Band-Gap Sn-Doped α-Ga2O3 Metal–Semiconductor Field-Effect Transistors

“…However, it is difficult to produce a β-Ga 2 O 3 wafer with a diameter large enough for practical application due to easy formation of cleavages such that the wafer size is limited to four inches [ 9 ]. Recently, mist chemical vapor deposition (Mist-CVD) has been introduced as a non-vacuum solution-process heteroepitaxy for α-Ga 2 O 3 on mass-produced sapphire (Al 2 O 3 ) wafers up to six inches, with a similar a crystal structure to α-Ga 2 O 3 [ 10 , 11 , 12 , 13 , 14 ]. Being able to lift α-Ga 2 O 3 off of the sapphire substrate and bond it to other substrates with high thermal conductivity (such as SiC, AlN, diamond, etc.)…”

Влияние ультрафиолетового излучения и электрического поля на проводимость структур на основе alpha- и ε-Ga-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-

“…Политип α-Ga 2 O 3 имеет структуру корунда и небольшую разницу в постоянных кристаллической решетки с сапфиром: 3.3% (c) и 4.5% (a) [9]. При этом α-Ga 2 O 3 обладает одной из самых больших шириной запрещенной зоны: E g = (5.1−5.3) эВ [10], что позволяет рассматривать его в качестве перспективного материала для создания солнечно-слепых детекторов в диапазоне глубокого УФ. В данной работе рассмотрено влияние структуры сапфировой подложки на электрические и фотоэлектрические характеристики слоев α-и ε-фаз оксида галлия.…”

Editorial for the Special Issue on ‘Metal Oxide Thin Film: Synthesis, Characterization, and Application’

“…This Special Issue is dedicated to these recent developments and contains 10 manuscripts reporting thin-film deposition and coating and their characterization. It compiles works on vapor-phase deposition processes including atomic-layer deposition (ALD) [ 1 , 2 ], mist-chemical-vapor deposition [ 3 ] and atmospheric-pressure chemical-vapor deposition (APCVD) [ 4 ] methods in which authors have studied the stabilization of metastable phases and the effect of growth conditions on thin film quality, epitaxy, and crystallinity. The Special Issue also includes liquid-phase coatings like sol-gel [ 5 ], solution immersion [ 6 ], micro-arc oxidation [ 7 ], Plasma Electrolytic Oxidation Processing [ 8 ], and single pulse anodization [ 9 ] where the authors were more focused on the coating of aluminum.…”

“…They showed that crystal orientations of the films can be tuned by the selection of the substrate and mitigated through the interface via solid-face epitaxy upon annealing. In the third manuscript, Xu et al report on the influence of carrier gases in mist chemical vapor deposition method on the quality of epitaxial corundum-structured α-Ga 2 O 3 films [ 3 ]. The thin films were grown on c-plane sapphire substrates with single (0006) plane orientation for all carrier gases, but the authors demonstrated that the O 2 gas enables the growth of better quality epitaxial films with increased growth rate (10.3 nm/min vs. 5.3 nm/min and 2.4 nm/min) and better crystalline quality.…”