Abstract:AlxGa1−xN films having various Al-contents were grown on (111) Si substrates over a temperature range of 800∼1000 °C. It was found that crack free AlxGa1−xN films were achieved when the films were grown at 800 °C. High temperature (HT) GaN films were also deposited on (111) Si substrates using 800 °C grown AlxGa1−xN buffer layers with different thickness and composition combinations. The best HT GaN film was achieved on (111) Si substrate by process optimization with an 800 °C grown 180 nm-thick Al0.58Ga0.42N buffer layer. Room temperature photoluminescence (PL) spectrum of the HT GaN film shows a strong near band edge emission having a linewidth of 100 meV and a quenched yellow luminescence. It is believed that the use of intermediate temperature AlxGa1−xN buffer layer is beneficial to accommodate the misfit strain between HT GaN film and (111) Si substrate.