InGaAs表面相变过程的MBE/STM研究

项目名称： InGaAs表面相变过程的MBE/STM研究

项目编号： No.60866001

项目类型： 地区科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 丁召

作者单位： 贵州大学

项目金额： 31万元

中文摘要： 通过对于In0.15Ga0.85As/GaAs薄膜在不同的衬底温度和As保护气压下的形貌演变，项目研究了In0.15Ga0.85As/GaAs薄膜的粗糙化过程。In0.15Ga0.85As薄膜中存在应力，在退火过程中，应力的释放是促使样品粗糙化的内在原因，In-As键的断裂和结合形成坑或岛将是应力释放的主要形式。在不同的温度和As压下，存在着In-As键的断裂和结合，断裂和结合的竞争在形貌上形成完全不同的粗糙化过程。低温低As压即断裂数目大于结合的时候，坑的形成成为薄膜表面粗糙化的主要推动力；反之即高温高As压，岛的形成将成为粗糙化的主要推动力；低温高As压下，表面维持平坦；高温低As压下，表面迅速进入粗糙化。同时发现，在InGaAs薄膜中，由于存在In的分凝（偏析）、脱附现象，样品的表面成分将发生明显的变化。 本项目完成了对于InGaAs材料的外延生长优化，特别是低In组分InGaAs的表面粗糙化和预粗糙化过程进行了深入研究。以此研究为基础，能够进一步扩展研究范围和领域，为研究化合物半导体量子点、量子线等低维材料以及自旋极化电子向半导体异质结构的注入等课题打下了坚实的基础。

中文关键词： InGaAs;粗糙化;MBE-STM;样品温度;As BEP

英文摘要： The roughening processes of In0.15Ga0.85As/GaAs films have been studied in this project. Under different As BEP and temperature, the surface morphology of In0.15Ga0.85As/GaAs films undergoes different procedures of evolution. Lattice mismatch made compressive strain in In0.15Ga0.85As/GaAs films, during annealing the strain release will play the critical role in the roughening processes of In0.15Ga0.85As/GaAs films. The formation and breaking of In-As bonds that formed pits and islands were the main ways of strain release. Under the different As BEP and temperature, the competition between formation and breaking of In-As bonds resulted in different roughening processes. When the number of break is more than that of formation (low temperature and low As BEP), pits were the primary impetus to make the surface from flat to rough. On the contrary, island would play the key role in the roughening process. Under low temperature and high As BEP, the surface would keep flat; the surface would roughen rapidly under the condition of low As BEP and high temperature. At the same time, we found that the composition of sample surface have changed obviously when the films roughened. Surface roughening and pre-roughening have been studied in detail, especially for low In composition of InGaAs films, optimized growth condition to epitaxy InGaAs films has been obtained in this project, which prompted the comprehension to surface physics of compound semiconductor. On the basis of this study, one can further expand the scope and areas, and this study will lay the foundation for research of compound semiconductor QDs, QWs and spintronics.

英文关键词： InGaAs;roughen;MBE-STM;substrate temperature;As BEP