|標題:||Characterization of 380 nm UV-LEDs grown on free-standing GaN by atmospheric-pressure metal-organic chemical vapor deposition|
|作者:||Shieh, C. Y.|
Li, Z. Y.
Kuo, H. C.
Chang, J. Y.
Chi, G. C.
Department of Photonics
|關鍵字:||indium clustering;internal quantum efficiency;efficiency droop;free-standing GaN substrate;UV LEDs|
|摘要:||We reported the defects and optical characterizations of the ultraviolet light-emitting diodes grown on free-standing GaN substrate (FS-GaN) and sapphire. Cross-sectional transmission electron microscopy (TEM) images showed that the total defect densities of grown UV LEDs on FS-GaN and sapphire including edge, screw and mixed type were 3.6x10(6) cm(-2) and 5.5x10(8) cm(-2). When substrate of UV LEDs was changed from sapphire to FS-GaN, it can be clearly found that the crystallography of GaN epilayers was drastically different from that GaN epilayers on sapphire. Besides, the microstructures or indium clustering can be not observed at UV LEDs on FS-GaN from TEM measurement. The internal quantum efficiency of UVLEDs on FS-GaN and sapphire were 34.8 % and 39.4 % respectively, which attributed to indium clustering in multi-layers quantum wells (MQWs) of UV LEDs on sapphire. The relationship between indium-clustering and efficiency droop were investigated by temperature-dependent electroluminescence (TDEL) measurements.|
|期刊:||GALLIUM NITRIDE MATERIALS AND DEVICES IX|
|Appears in Collections:||Conferences Paper|
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