As a promising third generation semiconductor material, gallium nitride (GaN) has become a research hotspot in optoelectronic field nowadays. In this paper, GaN thin films were grown by radio frequency (RF) planar magnetron sputtering of a powder GaN target in a pure nitrogen atmosphere at (0.2 – 2.0) Pa, (10 - 100) W onto various substrates such as GaAs (100), Si (100), Si (111), Al2O3(0001) and glass without any buffer layer. A clear phase transition from the metastable cubic zinc-blende (c - ZB) to the stable hexagonal wurtzite (h - WZ) dependence on substrates has been found in the GaN thin films. And the phase transition of GaN films were studied by X-ray diffraction (XRD), photoluminescence (PL) and Raman spectroscopy.

In this paper, we discuss the excitation module in the magnetic induction system. First, we start from the traditional sinusoidal input resonant excitation circuit and give the frequency domain equation of its excitation current. Then, we propose a new module based on pulse excitation and give the corresponding excitation equation in the frequency domain. After that, we deduce the mathematical model of excitation gain of new and old modules using application and technology and finally obtain intuitive mathematical analysis graphics for engineering promotion.