蓝宝石衬底上GaN薄膜的结构和光学特性表征

采用低压金属有机化学气相沉积(LPMOCVD)法,成功地在(0001)晶向的蓝宝石(Al2O3)衬底上制备了高质量的GaN薄膜.并利用X射线衍射(XRD)谱和椭圆偏振光谱(SE)对其结构和光学特性作了表征.XRD谱中,在34.5°和72.9°附近出现了两个尖锐的衍射峰,分析表明这两个衍射峰分别对应纤锌矿(Wurtzite) 结构GaN薄膜的(0002)和(0004)晶向.其中GaN (0002)晶向衍射峰的半高宽(FWHM)很窄,只有0.1°左右,并且GaN(0004)晶向衍射峰强度很强,二者均证实了采用LPMOCVD法制备的GaN薄膜具有高的质量.在介电函数和反射谱中,GaN高的透明性(＜3.44eV)诱导了强的干涉振荡.室温下拟合出的表征带间跃迁的光学带隙约为3.44eV.

Structural and Optical Properties Characterization of GaN Film Deposited on Sapphire Substrate

High-quality GaN film was successfully deposited on(0001)-oriented sapphire substrate by low-pressure metal-organic chemical vapor deposition(LPMOCVD) process.And its structural and optical properties were characterized by XRD,spectroscopic ellipsometry and reflectance spectra.Studied by XRD,the coexistence of strong(0002) diffraction peak with a very narrow FWHM value of 0.1 degree and high order GaN(0004) diffraction peak confirm the high quality of prepared GaN film.High optical transparency of GaN film induces strong interference oscillations below E_(0)(3.44 eV) in the measured dielectric function spectra and reflectance spectra.The fitted E_(0)value at room temperature is in good agreement with that reported in other papers.