LED用非极性GaN外延膜的制备技术进展

Progress in the Epitaxial Growth of Nonpolar GaN for LEDs

GaN是实现白光LED的关键材料。GaN外延膜通常沿极性c轴生长,基于极性GaN的LED有源层量子阱中由于强内建电场的存在而导致器件发光效率降低,而沿非极性面生长的GaN外延膜可以改善或消除极化效应导致的辐射复合效率降低和发光波长蓝移等问题。文章总结了非极性GaN外延膜的制备技术及研究进展,包括平面外延技术和横向外延过生长技术,指出开发非极性GaN自支撑衬底、发展非极性GaN的横向外延生长技术是制备低位错密度非极性GaN的研究方向。

GaN is the key material for white LED. GaN epitaxial films usually grow along the polar c axis, which results in the generation of polarization-induced built-in electric fields in the active layer quantum well. The polarization induced electric field causes a decrease in the quantum efficiency of LED. Nonpolar GaN materials can avoid the strong internal electric fields in active regions of LEDs and improve luminescence efficiency. The preparation techniques for nonpolar GaN epitaxial films, including planar growth and epitaxial lateral overgrowth （LEO） of a-plane and m-plane GaN films are summarized, and recent developments in both domestic and abroad are introduced. Free standing nonpolar GaN substrates and LEO technique for fabricating nonpolar GaN with low dislocation density should be further developed.