原子层沉积法制备高反射率的分布式布拉格反射镜

为提高GaN基发光二极管(LED)的发光强度,制备TiO₂/Al₂O₃分布式布拉格反射器(DBR)来提高其外量子效率是一种有效的方法。原子层沉积(ALD)法所制备的薄膜具有良好的均匀性,适合用来制备反射器材料。同时,TiN薄膜具有良好的类金属性质,且与TiO₂之间具有良好的粘附性,因此在DBR基础上再采用TiN反射层可以将反射率进一步提高。Matlab软件模拟结果表明,3~6周期厚的DBR,其反射率随厚度增加而提高。其中6周期DBR的反射率为95%,加上TiN薄膜后反射率可以得到进一步提高。实验结果与模拟结果吻合,6周期DBR+TiN结构的反射率达到99%。给带有该结构的LED注入50mA电流时,LED光输出功率(LOP)相对没有该结构的器件提升了约68.3%。

Preparation of High Reflectivity Distributed Bragg Mirrors Based on Atomic Layer Deposition

In order to improve the luminescence intensity of GaN-based light-emitting diodes (LEDs), it is an effective method to improve its external quantum efficiency by preparing TiO₂/Al₂O₃ distributed Bragg reflectors (DBR). Due to the good uniformity of the film prepared by ALD, it is suitable for the preparation of reflector materials. TiN film has good metalloid properties and good adhesion to TiO₂, therefore, the reflectivity can be further improved by using a TiN reflective layer on the basis of DBR. Simulations with Matlab software show that the reflectivity of DBR with 3~6 cycles increases with the increasing thickness of the film, in particular, that of DBR with 6 cycles is 95%, and it can be further improved with the introduction of TiN film. The experimental and simulation data show good agreement. The reflectivity of the structure of 6 DBR+TiN achieves 99% and when a current of 50mA was injected into the LED with this structure, its light output power (LOP) will be increased by about 68.3% compared to that of the device without such a modified structure.