蓝宝石衬底上生长的Ga2+xO3-x薄膜的结构分析

利用卢瑟夫背散射/沟道技术和金属有机化学气相沉积方法, 对蓝宝石衬底上 在不同温度、压强下生长的Ga_2+xO_3-x薄膜进行结构和结晶品质的测量与分析; 并结合高分辨X射线衍射分析技术, 通过对其对称(402)面的θ–2θ及ω扫描, 确定了其结构类型及结晶品质. 实验表明: 在相同的生长温度(500 ℃)下, 结晶品质随压强的下降而变好, 生长压强为15 Torr (1 Torr=133.322 Pa)的样品其结晶品质最好, 沿轴入射之比χ_min值为14.5%; 在相同的生长压强(15 Torr)下, 结晶品质受生长温度的影响不大, 所以, 生长温度不是改变结晶品质的主要因素; 此外, 在相同的生长条件下制备的样品, 分别经过700, 800和900 ℃退火后, 其结晶品质随退火温度的变化而变化. 退火温度为800 ℃的样品的结晶品质最好, χ_min值为11.1%; 当退火温度达到900 ℃时, 样品部分分解; 经热处理的样品其X射线衍射谱中有一个强的Ga₂O₃ (402)面衍射峰, 其半峰全宽为0.5°, 表明该Ga₂O₃外延膜是(402)择优取向. 关键词： 氧化镓 卢瑟夫背散射 X射线衍射 结晶品质

Structrual analyses of Ga2+xO3-x thin films grown on sapphire substrates

Ga_2+xO_3-x thin films grown on sapphire substrates by metal-organic chemical vapor deposition under different conditions (temperature pressure) are studied by rutherford backscattering spectrometry/channeling. The structural information and crystalline quality are further investigated by high resolution X-ray diffraction (HR-XRD). The results suggest that at the same growth-temperature the crystalline quality is improved with pressure decreasing, while χ_min reaches a minimum 14.5% when the pressure decreases to 15 Torr (1 Torr=133.322 Pa). Then if the pressure is kept at 15 Torr, all films present similar crystalline qualities, which hints that the temperature is not a chief factor. Moreover, films prepared under the same condition are annealed at different temperatures: 700, 800 and 900 ℃. At first the crystalline quality is improved by increasing the annealing temperature and reaches a best χ_min of 11.1%. Nevertheless, as the annealing temperature is further increased, the samples become decomposed. XRD spectra of annealed samples each reveal a strong peak of Ga₂O₃ (402), indicating that the epitaxial layer has a preferred orientation (402).