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研究了生长压力对金属有机物化学气相淀积技术在蓝宝石衬底上生长的GaN薄膜的生长速率、表面形貌和结晶质量的影响.研究结果表明,随着反应室压力由2500Pa增加到20000Pa,GaN薄膜表面逐渐粗化,生长速率逐渐下降.粗糙的表面形貌与初始高温GaN成核岛的特征密切相关.初始高温GaN生长阶段采用高压条件,因低的吸附原子表面扩散率而容易形成低密度、大尺寸的GaN岛.这些GaN岛推迟了二维生长过程的出现,降低了薄膜的生长速率.同时,这些低密度、大尺寸的GaN岛在此后生长合并过程中产生较少的线位错,从而降低了GaN薄膜X射线摇摆曲线的半高宽.
The effect of growth pressure on the growth rate, surface morphology and crystal quality of GaN thin films grown on sapphire substrate by metal organic chemical vapor deposition technique was studied.The results show that with the increase of reaction chamber pressure from 2500 Pa to 20000 Pa, The surface of the film gradually coarsens and the growth rate gradually decreases.The rough surface morphology is closely related to the characteristics of the initial high-temperature GaN nucleation island.The high-temperature GaN growth stage adopts high pressure conditions, which is easy to form a low density due to the low surface diffusion rate of the adsorbed atoms , Large size GaN islands.These GaN islands postponed the appearance of two-dimensional growth process and reduced the growth rate of the films.At the same time, these low-density, large-size GaN islands produced fewer line dislocations during subsequent growth and consolidation , Thus reducing the full width at half maximum of the X-ray rocking curve of the GaN film.