Xing Zhongqiu, Zhou Yongjie, Zhang Aoxiang, Qu Yipu, Wang Fang, Liou Juin J, Liu Yuhuai
National Center for International Joint Research of Electronic Materials and Systems, International Joint-Laboratory of Electronic Materials and Systems of Henan Province, School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou, 450001, Henan, People's Republic of China.
Basic Teaching Department, Zhengzhou University of Railway Engineering, Zhengzhou, 450001, Henan, People's Republic of China.
Sci Rep. 2024 Aug 2;14(1):17961. doi: 10.1038/s41598-024-69146-4.
The deep ultraviolet (DUV) micro-light emitting diode (μLED) has serious electron leakage and low hole injection efficiency. Meanwhile, with the decrease in the size of the LED chip, the plasma-assisted dry etching process will cause damage to the side wall of the mesa, which will form a carrier leakage channel and produce non-radiative recombination. All of these will reduce the photoelectric performance of μLED. To this end, this study introduces polarized bulk charges into the hole supply layer (p-HSL) and the electron supply layer (n-ESL) respectively (dual-polarized structure) of the DUV μLED at an emission wavelength of 279 nm to enhance the binding of carriers and increase the injection efficiency of carriers. This is because the polarization-induced bulk charge can shield the polarized sheet charge on the interface and reduce the polarization electric field. The reduced polarization electric field in p-HSL can increase the effective barrier height of the conduction band in the p-type region and reduce the effective barrier height of the valence band. The decrease in the polarized electric field of n-HSL can reduce the thermal velocity of electrons, thereby enhancing the electron injection efficiency, reducing the Shockley-Read-Hall (SRH) recombination, and increasing the effective barrier height of the valence band. The study results indicate that the electron concentration and hole concentration of a μLED with dual polarization were increased by 77.93% and 93.6%, respectively. The optical power and maximum external quantum efficiency of μLED reached 31.04 W/cm and 2.91% respectively, and the efficiency droop is only 2.06% at 120 A/cm. These results provide a new approach to solving the problem of insufficient carrier injection and SRH recombination in high-performance DUV μLEDs.
深紫外（DUV）微发光二极管（μLED）存在严重的电子泄漏和低空穴注入效率问题。同时，随着LED芯片尺寸的减小，等离子体辅助干法刻蚀工艺会对台面侧壁造成损伤，形成载流子泄漏通道并产生非辐射复合。所有这些都会降低μLED的光电性能。为此，本研究在发射波长为279 nm的DUV μLED的空穴供应层（p-HSL）和电子供应层（n-ESL）中分别引入极化体电荷（双极化结构），以增强载流子的结合并提高载流子的注入效率。这是因为极化诱导的体电荷可以屏蔽界面上的极化面电荷并降低极化电场。p-HSL中极化电场的降低可以增加p型区域导带的有效势垒高度并降低价带的有效势垒高度。n-HSL极化电场的降低可以降低电子的热速度，从而提高电子注入效率，减少肖克利-里德-霍尔（SRH）复合，并增加价带的有效势垒高度。研究结果表明，具有双极化的μLED的电子浓度和空穴浓度分别提高了77.93%和93.6%。μLED的光功率和最大外量子效率分别达到31.04 W/cm和2.91%，在120 A/cm时效率 droop仅为2.06%。这些结果为解决高性能DUV μLED中载流子注入不足和SRH复合问题提供了一种新方法。
