Dependence of oxygen impurity concentration in AlN on the surface roughness during growth

Abstract

In the cathode luminescence spectroscopic study of AlN thin films grown on c-plane sapphire, we found that the luminescence of 3–4 eV is correlated with O impurities, and it is first enhanced and then weakened with the increase in the temperature. The results of an SIMS test show that the concentration of O impurities in the samples is weakly correlated with the growth conditions but strongly correlated with the surface roughness of the samples at the time of growth. The rougher surface exposes more crystalline plane to the growth environment and different crystalline planes have different absorption capacities for O impurities, leading to an inhomogeneous distribution of O impurities in AlN. This inhomogeneous distribution results in a specific variation in the luminescence intensity of O impurities with temperature.