Quantum-Function Spinics Laboratory, Department of Physics, Hanyang University, Seoul, Korea.
Nanotechnology. 2010 Apr 2;21(13):134026. doi: 10.1088/0957-4484/21/13/134026. Epub 2010 Mar 8.
The potential of nonpolar a-plane InGaN/GaN multi-quantum wells (MQWs), which are free from a strong piezoelectric field, was demonstrated. An a-GaN template grown on an r-plane sapphire substrate by the multi-buffer layer technique showed high structural quality with an omega full width at half maximum value along the c-axis of 418 arcsec obtained from high-resolution x-ray diffraction analysis. From barrier analysis by deep level transient spectroscopy, it appeared that a-plane InGaN/GaN MQWs can solve the efficiency droop problem as they have a lower electron capture barrier than the c-plane sample. The peak shift of the temperature-dependent photoluminescence signal for the nonpolar InGaN/GaN MQWs was well fitted by Varshni's empirical equation with zero-internal fields. A high photoluminescence efficiency of 0.27 from this sample also showed that nonpolar MQWs can be the key factor to solve the efficiency limitation in conventional c-plane GaN based light emitting diodes.
非极性 a 面 InGaN/GaN 多量子阱（MQWs）具有消除强压电场的潜力，这一点得到了证明。采用多缓冲层技术在 r 面蓝宝石衬底上生长的 a-GaN 模板在 c 轴方向上的ω全宽半最大值达到了 418 弧秒，这表明其具有很高的结构质量，这一结果是通过高分辨率 X 射线衍射分析得到的。从深能级瞬态光谱的势垒分析来看，a 面 InGaN/GaN MQWs 似乎可以解决效率下降的问题，因为它们的电子俘获势垒比 c 面样品低。非极性 InGaN/GaN MQWs 的温度依赖光致发光信号的峰值位移很好地符合了零内场的 Varshni 经验方程。该样品的高光致发光效率为 0.27，这表明非极性 MQWs 可能是解决传统 c 面 GaN 基发光二极管效率限制的关键因素。
