Absorption and Reflection of Vapor Grown Single Crystal Platelets of β-Ga2O3

Absorption and reflection spectra of β-Ga 2 O 3 are measured with polarized light in the wavelength region near its absorption edge. The crystals of β-Ga 2 O 3 are grown by using a Ga/HCl/O 2 /Ar vapor reaction system. The platelike crystals of β-Ga 2 O 3 have (100), (010), and (001) surfaces, and the major surface is (100). The energies of the absorption edge are observed to be 4.90 eV for E// b , 4.54 eV for E// c , and 4.56 eV for E⊥ b & c at room temperature. The energies for E// b and for E// c at 77 K are larger than those at room temperature by 40 meV and 220 meV, respectively. Reflection minima are observed at 5.06 eV and 5.30 eV for E// b , and at 4.63 eV and 5.30 eV for E// c at room temperature.