POLARITY DETERMINATION OF A GAN THIN-FILM ON SAPPHIRE (0001) WITH X-RAY STANDING WAVES

The x-ray standing wave technique was used to determine the polarity o f a 1 mu m thick GaN film grown by molecular beam epitaxy on an alpha- Al2O3(0001) single crystal. The standing wave was generated by x-ray d iffraction from the GaN film, The Ga K-alpha fluorescence yield was re corded as a function of incidence angle within the range of the GaN(00 02) reflection. Analysis of the data reveals that the film has grown w ith N polarity, i.e., the nitrogen atoms occupy the top half of the wu rtzite (0001) bilayers. (C) 1998 American Institute of Physics.