气压对 PLD 法在AlN/Si 上外延生长的GaN性能的影响∗

摘要

采用脉冲激光沉积(PLD)技术在AlN/Si异质结上外延生长GaN薄膜.研究了气压对GaN薄膜结构性能和表面形貌的影响,利用高分辨 X射线衍射仪(HRXRD)、原子力显微镜(AFM)和扫描电子显微镜(SEM)对 GaN薄膜的结构性能及表面形貌等进行表征和分析.结果表明：气压在1~50 mTorr 范围时,GaN薄膜的表面形貌及结构性能均是先好后差；当气压在最佳值10 mTorr 时,外延生长的 GaN薄膜质量最优,其(0002)和(1012)面的高分辨 X射线衍射摇摆曲线峰值半高宽(FWHM)分别为0.7°和0.8°；原子力显微镜测试得到 GaN薄膜表面的粗糙度为1.8 nm.%The GaN films have been grown on AlN/Si (1 1 1 )hetero-structures by pulsed laser deposition (PLD)and the effect of nitrogen pressure on the structural properties and the surface morphologies of GaN films is investigated.High resolution X-ray diffraction (HRXRD),atomic force microscope (AFM)and scanning electron microscope (SEM)are used to characterize and analyze the structural properties and the surface morphologies of GaN films.When the nitrogen pressure changes from 1mTorr to 50 mTorr,the structural properties and the surface morphologies of GaN films are improved at first, and then deteriorated.Meanwhile,it shows an optimum value of 10 mTorr pressure,the as-grown GaN reveals that the full-width at half-maximum (FWHM)of GaN (0002)and (1012)is 0.7°and 0.8°,respectively,and very smooth surface with a root-mean square (RMS)surface roughness of 1 .8 nm,indicating high-quality GaN films.