Investigations on epitaxy and lattice distortion of sputter deposited β-Ga2O3layers on GaN templates

The lattice distortion and epitaxial nature of beta-Ga(2)O(3)layers deposited on GaN templates using radio-frequency magnetron sputtering have been evaluated. The determined values of out-of-plane (tensile type) and in-plane (compressive type) strain are found to decrease with increase in deposition temperature, indicating better relaxation of the unit cell lattice at higher temperatures. The obtained value of angle beta is invariably higher than its bulk value, suggesting a distortion in the unit cell of beta-Ga(2)O(3)layer. Columnar-type growth for beta-Ga(2)O(3)layer on GaN template has been observed. Analysis of its epitaxial nature reveals that six domains of grown layer are in-plane rotated by 60 degrees +/- delta(o)(delta = 2 degrees-3 degrees) with each other, which is explained by the presence of three non-equivalent oxygen atoms on the (-201) plane of beta-Ga2O3. The calculated values of delta nearly match experimentally observed values. However, the smaller difference between the two is related to residual strain in the layer. The out-of-plane and in-plane epitaxial relationship for beta-Ga(2)O(3)layer with respect to GaN are (-201)(Ga2O3)|| (0001)(GaN)and (010)(Ga2O3)|| (11-20)(GaN), respectively.