Investigation of Sn Incorporation in β-Ga2O3 Single Crystals and its Effect on Structural and Optical Properties

Abstract

Undoped and Sn-doped β-Ga2O3 single crystals were grown by optical floating zone technique by varying the doping concentration of Sn from 0.05 wt% to 0.2 wt%. Uniform distribution of the dopant ions was achieved by heat treatment. The crystalline quality and the expansion of the lattice were observed from the PXRD. Raman spectra reveals the incorporation of Sn atoms into the lattice by replacing Ga in the octahedral site. The interplanar distance (d) was calculated as 2.39 Å from the HR-TEM micrographs. The transmittance was found to be decreasing from 80% to 78% as the concentration of Sn increases. The absorption spectra shows a cut off edge around 260 nm for undoped and 270 nm for all Sn doped samples. The bandgap obtained for undoped β-Ga2O3 was 4.36 eV. The doping of 0.05 wt% of Sn decrease the value of bandgap to 4.08 eV, but, for 0.1 wt% and 0.2 wt% Sn an increase in the bandgap value of 4.13 eV and 4.20 eV was observed respectively. The refractive index was found to be 1.96 at 500 nm wavelength. The increase in Sn concentration results in increase of the roughness from 1.116 nm to 3.511 nm.