Poyiatzis N, Athanasiou M, Bai J, Gong Y, Wang T
Department of Electronic and Electrical Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD, United Kingdom.
Sci Rep. 2019 Feb 4;9(1):1383. doi: 10.1038/s41598-018-37008-5.
Carrier transport issues in a (11-22) semi-polar GaN based white light emitting diode (consisting of yellow and blue emissions) have been investigated by detailed simulations, demonstrating that the growth order of yellow and blue InGaN quantum wells plays a critically important role in achieving white emission. The growth order needs to be yellow InGaN quantum wells first and then a blue InGaN quantum well after the growth of n-type GaN. The fundamental reason is due to the poor hole concentration distribution across the whole InGaN quantum well region. In order to effectively capture holes in both the yellow InGaN quantum wells and the blue InGaN quantum well, a thin GaN spacer has been introduced prior to the blue InGaN quantum well. The detailed simulations of the band diagram and the hole concentration distribution across the yellow and the blue quantum wells have been conducted, showing that the thin GaN spacer can effectively balance the hole concentration between the yellow and the blue InGaN quantum wells, eventually determining their relative intensity between the yellow and the blue emissions. Based on this simulation, we have demonstrated a monolithically multi-colour LED grown on our high quality semi-polar (11-22) GaN templates.
通过详细模拟研究了基于半极性（11-22）GaN的白光发光二极管（由黄色和蓝色发射组成）中的载流子输运问题，结果表明黄色和蓝色InGaN量子阱的生长顺序在实现白光发射中起着至关重要的作用。生长顺序需要先生长黄色InGaN量子阱，然后在n型GaN生长之后生长蓝色InGaN量子阱。根本原因是整个InGaN量子阱区域的空穴浓度分布不佳。为了在黄色InGaN量子阱和蓝色InGaN量子阱中都有效地捕获空穴，在蓝色InGaN量子阱之前引入了一层薄的GaN间隔层。对能带图以及黄色和蓝色量子阱中的空穴浓度分布进行了详细模拟，结果表明薄的GaN间隔层可以有效地平衡黄色和蓝色InGaN量子阱之间的空穴浓度，最终确定它们在黄色和蓝色发射之间的相对强度。基于此模拟，我们展示了在高质量半极性（11-22）GaN模板上生长的单片多色发光二极管。
