Influence of stacking faults on the properties of GaN-based UV light-emitting diodes grown on non-polar substrates

摘要

We report on the reduction of defect densities in non-polar a-plane GaN films over r-plane sapphire achieved by epitaxial laterally overgrowth (ELOG) approach. A mask pattern was used to produce ELOG GaN with wing region width of about 30μm. Based on transmission electron microscopy (TEM) results, the window regions have stacking faults density of ～10~6cm~(-1) and threading dislocation density of ～10~(10)cm~(-2). Both ELOG Ga-face and N-face wing regions have stacking fault density of ～10~5 cm~(-1), and dislocation density less than 10~8 cm~(-2). Cathodoluminescence studies reveal the difference in defect densities between N-faced and Ga-faced wings. GaN-based UV light-emitting diode formed on Ga-faced wing shows stronger quantum well emission and weaker parasitic emission than that formed on N-faced wing.