Temperature dependence of stresses in GaN thin films grown on (0001) sapphire: Modeling of thermal stresses

Residual stresses and unstressed lattice parameters are characterized in heteroepitaxial GaN thin films grown on (0001) sapphire using three different deposition techniques. X-ray diffraction measurements in the temperature range of 25–600 °C indicate a reversible change of stresses in the films from compressive to tensile state and vice versa. The thermal behavior of stresses in the samples prepared by different methods is comparable. The experimental results are consistent with the model of thermal stresses originating from the mismatch of thermal expansion coefficients of GaN and sapphire.