Electrical and optical properties and defects of (100)- and (001)-oriented V-doped 8-Ga2O3 crystals grown by EFG

Altering the n-type conductivity and optical properties of ultra-wide bandgap 8-Ga2O3 by impurity doping has been a topic of research interest in the semiconductor field. Simultaneously, 8-Ga2O3 with a monoclinic structure has exhibited interesting anisotropy. In this study, (100) and (001) V-doped 8-Ga2O3 crystals were synthesized by the edge-defined film-fed growth (EFG) method, and their structural, electrical and optical properties, and de-fects were systematically investigated. V-doped 8-Ga2O3 crystals with a (100) plane have a better crystalline quality and flatter surface than those with a (001) plane. Compared with undoped crystals (-1016 cm-3), the carrier concentration of the (100) and (001) V-doped 8-Ga2O3 substrates only increased to 4.30 x 1017 cm-3 and 1.92 x 1017 cm-3 , respectively, which was related to the VxOy clusters formed by excess V as trapping traps and the carbon DX center as an electron capture trap formed by the relaxation of C atoms in the direction opposite to that of the C-O bond. The generation of absorption peaks and flat regions in the transmittance spectra was attributed to the introduction of V doping. The etch pit morphology and Raman peak intensity on the surfaces of the (100) and (001) V-doped 8-Ga2O3 substrates were different owing to the anisotropy of the monoclinic lattice structure. These results contribute to the understanding of the influence of V and anisotropy on 8-Ga2O3 crystals and expand their applications in electrical and optical fields.