Kim Sang-Jo, Lee Kwang Jae, Oh Semi, Han Jang-Hwang, Lee Dong-Seon, Park Seong-Ju
Opt Express. 2019 Apr 15;27(8):A458-A467. doi: 10.1364/OE.27.00A458.
We report the enhanced optical and electrical properties of InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs) with strain-relaxing Ga-doped ZnO transparent conducting layers (TCLs). Ga-doped ZnO was epitaxially grown on p-GaN by metal-organic chemical vapor deposition. The optical output power of a LED with a 500-nm- thick-Ga-doped ZnO TCL increased by 30.9% at 100 mA, compared with that of an LED with an indium tin oxide (ITO) TCL. Raman spectroscopy measurement and the simulation of wavefunction overlap of electron and hole in MQWs revealed that the enhanced optical output power was attributed to the increased internal quantum efficiency due to the decreased compressive strain in the active region. The increase of optical output was also attributed to the increased optical transmittance of the Ga-doped ZnO TCL owing to its higher refractive index compared to that of ITO TCL. Furthermore, the forward voltage of LED with a Ga-doped ZnO TCL was lower than that of LED with an ITO TCL because of the increased carrier concentration and mobility in the Ga-doped ZnO TCL.
我们报道了具有应变弛豫Ga掺杂ZnO透明导电层（TCL）的InGaN/GaN多量子阱（MQW）发光二极管（LED）的光学和电学性能增强的情况。通过金属有机化学气相沉积在p-GaN上外延生长Ga掺杂的ZnO。与具有氧化铟锡（ITO）TCL的LED相比，具有500nm厚Ga掺杂ZnO TCL的LED在100mA时的光输出功率提高了30.9%。拉曼光谱测量以及对MQW中电子和空穴波函数重叠的模拟表明，光输出功率增强归因于有源区压缩应变降低导致内部量子效率提高。光输出的增加还归因于Ga掺杂ZnO TCL的光学透过率增加，这是因为其折射率高于ITO TCL。此外，由于Ga掺杂ZnO TCL中载流子浓度和迁移率增加，具有Ga掺杂ZnO TCL的LED的正向电压低于具有ITO TCL的LED。
