【摘要】 用ＲＢＳ／沟道技术对ＭＯＣＶＤ生长的未故意掺杂的ＧａＮ的结构性能进行了测试，同时用霍耳方法测试了样品的电学性能。结果表明：ＧａＮ薄膜的背散射沟道谱与随机谱之比Ｘｍｉｎ和其补偿度存在一定的依赖关系。补偿度小的样品，其Ｘｍｉｎ小；随着样品补偿度的增大，Ｘｍｉｎ也逐渐增大；但它们之间的关系变化是非线性的。对这些结果给予了一定的解释。更多还原

【Abstract】 The structure of unintentionally doped GaN grown by organometallic vapor phase epitaxy on Al2O3 substrates was investigated using Rutherford Backscattering and Ion Channeling measurements. The growth of unintentionally doped GaN films was performed by MOCVD method using a home-made vertical reactor operating at atmospheric pressure. The grwoth was carried out on (0001 ) oriented sapphire substrates using Trimethylgallium (TMGa) and blue-ammonia (NH3) as Ga and N sources, respectively. The mixed gases of hydrogen and nitropen were used as the damer gases. A thin buffer layer with thickness of about 15um was grown at 520t and recrystallized at 1 060℃ for 6 minutes. The GaN films were grown at 1 060℃. Rutherfold Backscattering and Channeling spectra were measured with 2 .0meV He+ ions at a scattering angle of 165°.The ion channeling minimum yields in the near-surface region (the ratio of the backscattered yield along the random direction to that of the aligned, Xmin) for four samples were 1. 43 %, 2. 13 %, 2. 22 % and 29. 8 %, respectively. The electrical properties of those films were measured by Van der Pauw Hall method, and their compensation ratio were 0. 45, 0. 6, 0. 83 and 0. 9, respectively. The results indicats that there existed some relationship between Xmin and the compensation ratio, and the relation was unambiguous for thin films. The value of Xmin was small in GaN with light compensation ratio, while it was large in GaN with heavy compensation ratio, but the growth in value Of Xmin with increasing of compensation ratios was seen to be nonlinear. The experimental results were analyzed as following: high compensation suggested that there were many acceptor impurities or defects in epitaxial films of GaN. When those acceptor impurities or defects were interstitial, the incident He+ ions would endure great scattering so that the channeled yields would increase remarkably. But as for thick epitaxial film, most part of defects were located near the interface between film and substrate, so it was possible that the crystalline quality near the film surface would be improved. In this case, the growth of compensation didn’ t result in alarge increment of Xmin. However, in the thin films with heavy compensation, some cases were different. The acceptor impurities or defects were to be distributed over the whole epitaxial film, and near surface there still existed many impurites or defects, therefore, the value of Xmin would increase greatly.更多还原