Comprehensive study of blue and green multi-quantum-well light-emitting diodes grown on conventional and lateral epitaxial overgrowth GaN
Comprehensive study of blue and green multi-quantum-well light-emitting diodes grown on conventional and lateral epitaxial overgrowth GaN
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DOI：
10.1007/s00340-008-3321-y
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发表时间：
2009-05-01
影响因子：
2.1
通讯作者：
Razeghi, M.
中科院分区：
文献类型：
--
作者：
Bayram, C.;Pau, J. L.;Razeghi, M.
在横向外延过生长 (LEO) GaN 上实现了蓝色和绿色多量子阱 (MQW) 和发光二极管 (LED) 的生长，并与在传统 GaN 上生长的相同结构进行了比较。原子力显微镜用于确认我们的 LEO 样品翼区在活性区域生长之前位错的显着减少。分析了蓝色和绿色 MQW 表面形貌的差异。这些 MQW 集成到 LED 中。所有器件都显示出电致发光 (EL) 峰值发生蓝移，并且随着注入电流的增加，EL 光谱变窄，这两个特性均归因于带隙重整化。绿色 LED 分别由于 MQW 中更大的压电场和更多的铟偏析而表现出更大的 EL 峰值偏移和更宽的 EL 光谱。 LEO GaN 上的蓝色 LED 表现出比传统 GaN 上的蓝色 LED 更高的性能；然而，LEO GaN 上的绿色 LED 与传统 GaN 上的绿色 LED 没有观察到性能差异。绿色 LED 的性能主要受到有源层生长质量的限制。
Growths of blue and green multi-quantum wells (MQWs) and light-emitting diodes (LEDs) are realized on lateral epitaxial overgrowth (LEO) GaN, and compared with identical structures grown on conventional GaN. Atomic force microscopy is used to confirm the significant reduction of dislocations in the wing region of our LEO samples before active-region growth. Differences between surface morphologies of blue and green MQWs are analyzed. These MQWs are integrated into LEDs. All devices show a blue shift in the electroluminescence (EL) peak and narrowing in EL spectra with increasing injection current, both characteristics attributed to the band-gap renormalization. Green LEDs show a larger EL peak shift and a broader EL spectrum due to larger piezoelectric field and more indium segregation in the MQWs, respectively. Blue LEDs on LEO GaN show a higher performance than those on conventional GaN; however, no performance difference is observed for green LEDs on LEO GaN versus conventional GaN. The performance of the green LEDs is shown to be primarily limited by the active layer growth quality.