Evaluation of the crystalline quality of b-Ga(2)O(3) films by optical absorption measurements

Si doped b-Ga(2)O(3) films were grown on Si substrate by RF magnetron sputtering. The Si concentration varied from 0% to 50%. After the deposition of the amorphous Ga(2)O(3) on the substrate, thermal annealing at 600 'C was performed in nitrogen ambient. Polycrystalline b-Ga(2)O(3) films were grown on Si or quartz substrates; however, other mixed phases of Si, Ga and O were not observed. From the measurement of optical absorption coefficient, it is concluded that the b-Ga(2)O(3) energy gap increases with increasing Si concentration in the deposited film.