Heteroepitaxial β-Ga₂O₃ thick films on sapphire substrate by carbothermal reduction rapid growth method

Abstract

The heteroepitaxial β-Ga2O3 thick films were rapidly grown on various oriented sapphire substrate using carbothermal reduction method. The β-Ga2O3 films were prepared in our home-made vertical dual temperature zone furnace. The growth direction as well as surface morphology show the strong dependence on the orientation of the sapphire substrate. The fastest growth rate was obtained reaching approximate 15 μm/h on c-plane sapphire substrate according to the average 30 μm thickness of β-Ga2O3 films grown for 2h measured by cross-section scanning electron microscope. The Raman spectra indicate the pure-phase β-Ga2O3 films without obvious strain. The bandgap for grown films were in range of 4.65-4.7 eV confirmed by X-ray photoelectron spectra and Tauc plot from absorption spectra. Secondary ion mass spectrometry was used to check the impurities indicating a limited amount of residual carbon inside the films even though graphite as the reducing agent. The results in this work give promising alternative method of rapid epitaxial β-Ga2O3 thick film for the application on high-power electronic devices.

A Review of Recent Progress in β‐Ga2O3 Epitaxial Growth: Effect of Substrate Orientation and Precursors in Metal–Organic Chemical Vapor Deposition

“…The carbothermal reduction is another way to grow β-Ga 2 O 3 at higher growth rate (>5 μm), but the observed RT mobility was only 22.5 cm 2 V À1 s À1 at background carrier concentration of 10 15 cm À3 . [86] 4.2. MOCVD Growth of β-Ga 2 O 3 MOCVD is the standard manufacture preferred epitaxial technique for growth of III-V, III-VI-, and II-VI-based optoelectronic and power devices.…”

“…The carbothermal reduction is another way to grow β‐Ga 2 O 3 at higher growth rate (>5 μm), but the observed RT mobility was only 22.5 cm 2 V −1 s −1 at background carrier concentration of 10 15 cm −3 . [ 86 ]…”

The Heteroepitaxy of Thick β-Ga2O3 Film on Sapphire Substrate with a β-(AlxGa1−x)2O3 Intermediate Buffer Layer

“…Compared with β -Ga 2 O 3 substrate, sapphire is an economic and cost-effective substrate for heteroepitaxy. Several groups have attempted to synthesize β -Ga 2 O 3 on sapphire substrate using various methods, including pulsed layer deposition (PLD) [ 8 ], molecular beam epitaxy (MBE) [ 4 , 9 ], halide vapor phase epitaxy (HVPE) [ 3 , 10 ], carbothermal reduction [ 11 ], metal organic chemical vapor deposition (MOCVD) [ 12 , 13 ], and low-pressure chemical vapor deposition (LPCVD) [ 14 ]. PLD and MBE, allowing for precision controllability, are able to achieve high-quality β -Ga 2 O 3 films on sapphire.…”

“…The distribution of Al components in the film was homogenous, with an Al content of approximately 62%. After synthesizing the β -(Al x Ga 1−x ) 2 O 3 buffer layer, the β -Ga 2 O 3 thick film was further deposited on the β -(Al x Ga 1−x ) 2 O 3 /sapphire template using two methods: carbothermal reduction, reported recently by our group [ 11 ], and HVPE. Finally, we characterized the properties of the β -Ga 2 O 3 thick film on sapphire with and without the β -(Al x Ga 1−x ) 2 O 3 buffer layer.…”