采用低流量III族Ga束流在分子束外延中低温辅助清理GaAs衬底表面氧化物。采用高能电子衍射监控衬底表面氧化物清理过程并得出氧化物清理速率及氧化层对高能电子的吸收系数。根据清理速率对衬底温度依赖的Arrhenius关系，估算了Ga辅助清理过程中发生化学反应所需要的活化能。Ga束流辅助清理衬底表面氧化物技术在外延生长中具有实际可应用性。用这项技术清理外延GaAs衬底，仅通过生长十几纳米厚的GaAs缓冲层，就能够重复地获得高质量低密度InAs量子点。另外，采用这项技术良好地保持了外延衬底的原有表面特性，相信它在需要保持良好界面特性的器件结构外延再生长中也将具有特别的潜在应用价值。

Ga-assisted desorption of native surface oxide on GaAs substrate is investigated at low substrate temperature. The progress is monitored by reflection high energy electron diffraction (RHEED), and time dependence of RHEED intensity curves is recorded by a CCD camera. By fitting the curves, the oxide desorption rates are deduced, which depend strongly on the substrate temperature and can be fitted well by Arrhenius relationship. Furthermore, the absorption coefficients of the oxide layer to the high energy electron are estimated. The feasibility of using Ga-assisted desorption for overgrowth is confirmed by growth of high quality low-density InAs quantum dot samples. The result suggests that Ga-assisted desorption is extremely promising for the overgrowth, where a smooth interface is needed to be well preserved.