不同速度下砷化镓纳米划擦中表面与亚表面损伤机理研究

Study on Surface and Subsurface Damage Mechanism of GaAs Nanoscratching at Different Speed

为了进一步改进砷化镓激光器谐振腔面的制造技术,采用分子动力学方法模拟了砷化镓激光器的刻划过程。生成了不同取向的GaAs晶体模型,包括GaAs[100]、GaAs[110]和GaAs[111],并对这些模型进行了不同加工速度下的划痕模拟。基于仿真结果,分析了划痕、损伤宽度、亚表面损伤、堆高、位错分布和活动性等表面特征。结果表明,在砷化镓的刻划过程中,不同晶向的变形具有明显的各向异性。砷化镓晶体刮擦过程中的表面特征、损伤宽度、亚表面损伤和位错动力学与晶体取向密切相关。此外,增加加工的速度可以减小最大损伤宽度、提高堆叠高度,有利于提高材料去除率,但却会使表面质量略微降低,这一点适用于三个晶向。对于亚表面而言,随着划擦速度的增加亚表面损伤层的厚度会减小,这一点仅适用于GaAs[110]和GaAs[111]晶向,GaAs[100]晶向的亚表面损伤层厚度对速度的变化并不敏感;同时速度的增加会减小砷化镓亚表层中的完美位错长度和总长度,但对位错类型基本没有影响。

In order to further improve the fabrication technology of the cavity surface of GaAs laser,the engraving process of GaAs laser was simulated by molecular dynamics method.GaAs crystal models with different orientations,including GaAs[100],GaAs[110]and GaAs[111],were generated,and the scratch simulation of these models was carried out at different processing speeds.Based on the simulation results,surface characteristics such as scratches,damage width,subsurface damage,stacking height,dislocation distribution and activity were analyzed.The results show that the deformation of different crystal direction has obvious anisotropy during GaAs carving.The surface characteristics,damage width,subsurface damage and dislocation dynamics of gallium arsenide crystal during the scraping process are closely related to crystal orientation.In addition,increasing the processing speed can reduce the maximum damage width and increase the stacking height,which is conducive to improving the material removal rate,but will slightly reduce the surface quality,which is applicable to the three crystal directions.For the subsurface,the thickness of the subsurface damage layer decreases with the increase of the scratch velocity,which is only applicable to GaAs[110]and GaAs[111]crystal direction,and the thickness of the subsurface damage layer of GaAs[100]crystal direction is not sensitive to the change of the velocity.At the same time,the increase of speed can reduce the length of the perfect dislocation and the total length of the GaAs sublayer,but has no effect on the dislocation type.