激光剥离GaN表面的抛光技术

Polishing of Laser Lift-Off-Induced GaN Surface

激光剥离(LLO)技术是研制新型氮化镓(GaN)基谐振腔结构光电子器件的关键技术。然而LLO后的GaN表面往往具有较大的粗糙度,而制作谐振腔结构器件需要很高的表面平整度,因此需要对LLO后的GaN表面进行抛光。分别采用金刚石粉抛光液和胶粒二氧化硅抛光液进行机械抛光和化学机械抛光(CMP),并对比了两种方法获得的抛光结果,研究发现前者会在抛光后的GaN表面引入划痕,而采用后者可以得到亚纳米级平整度的表面。进一步的实验结果表明,胶粒二氧化硅抛光液同样适用于图形化衬底外延片激光剥离后的GaN表面抛光。

Laser lift-off（ LLO） is a key technology in development of new GaN-based resonant-cavity optoelectronic devices. For cavity-dependent devices,a smooth surface is highly required. However,the GaN surface after LLO is usually rough,and the polishing is necessary. The mechanical polishing of diamond powder and the chemical mechanical polishing of colloidal silica were compared. It is found that diamond powder leads to scratches on the GaN surface whereas colloidal silica leads to smooth surface with sub-nanometer roughness. The experiment results indicate that polishing with colloidal silica solutions can be applied to smoothen the LLO-produced GaN surface from an epitaxial wafer grown on patterned-sapphire substrate.