在GaN薄膜表面电镀厚100μm的、均匀的金属铜作为转移衬底。采用激光剥离技术,在400mJ/cm^2脉冲激光能量密度条件下,成功地将GaN薄膜从蓝宝石衬底转移至Cu衬底。激光剥离后Cu衬底上GaN薄膜的扫描电子显微镜(SEM)测试结果表明,电镀Cu衬底与GaN之间形成致密的结合,对GaN薄膜起到了很好的支撑作用。同时铜的延展性好,使得GaN薄膜内产生的应力得到有效释放,保持了剥离后GaN薄膜的完整性。激光剥离后GaN表面残留物的X射线光电子能谱(XPS)分析显示,激光辐照产生的金属Ga部分与空气中的氧结合形成Ga2O3,这是剥离后GaN表面后处理困难的原因,并给出了相应的解决方法。
100μm thick Cu substrate was deposited on the GaN surface by electroplating. Using the pulse laser at the energy density of 400mJ/cm^2, the GaN film was successfully transferred from sapphire to Cu. The scanning electron microscopy (SEM) images of the GaN film on Cu indicate that the electroplating Cu substrate formed compact boding with the GaN fdm and supported the film firmly during the laser lifit-off process, The GaN kept intact due to the excellent ductibility of the Cu substrate by releasing the strain stress producing by the laser lift-off in GaN film effectively. The X-ray electron spectroscopy (XPS) result shows that part of the metal Ga produced by laser irradiation was oxidated to Ga2O3 when exposing to the air. This will cause troubles for GaN surface cleaning. Related surface treatment method was given in the paper.