Nearly Lattice-Matched GaN Distributed Bragg Reflectors with Enhanced Performance

Materials

Ce Xu¹  Guillem Martinez de Arriba¹  Tao Wang¹  Xinchi Chen¹  Peng Feng¹  Chenqi Zhu¹  Ye Tian¹  Volkan Esendag¹ 

[1] Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield S1 3JD, UK;

关键词: AlGaN/GaN;    distributed Bragg reflector;    electrochemical etching;    nanoporous structure;   

DOI  :  10.3390/ma15103536

来源: DOAJ

【 摘 要 】

Heavy silicon-doping in GaN generally causes a rough surface and saturated conductivity, while heavily silicon-doped n++-AlGaN with ≤5% aluminum can maintain an atomically flat surface and exhibit enhanced conductivity. Given this major advantage, we propose using multiple pairs of heavily silicon-doped n++-Al_0.01Ga_0.99N and undoped GaN instead of widely used multiple pairs of heavily silicon-doped n++-GaN and undoped GaN for the fabrication of a lattice-matched distributed Bragg reflector (DBR) by using an electrochemical (EC) etching technique, where the lattice mismatch between Al_0.01Ga_0.99N and GaN can be safely ignored. By means of using the EC etching technique, the n++-layers can be converted into nanoporous (NP) layers whilst the undoped GaN remains intact, leading to a significantly high contrast in refractive index between NP-layer and undoped GaN and thus forming a DBR. Our work demonstrates that the NP-Al_0.01Ga_0.99N/undoped GaN-based DBR exhibits a much smoother surface, enhanced reflectivity and a wider stopband than the NP-GaN/undoped GaN-based DBR. Furthermore, the NP-Al_0.01Ga_0.99N/undoped GaN-based DBR sample with a large size (up to 1 mm in width) can be obtained, while a standard NP-GaN/undoped GaN-based DBR sample obtained is typically on a scale of a few 100 μm in width. Finally, a series of DBR structures with high performance, ranging from blue to dark yellow, was demonstrated by using multiple pairs of n++-Al_0.01Ga_0.99N and undoped GaN.

【 授权许可】

Unknown