Gao Yaqi, Yang Jiankun, Ji Xiaoli, He Rui, Yan Jianchang, Wang Junxi, Wei Tongbo
State Key Laboratory of Solid-State Lighting, Institute of Semiconductors, University of Chinese Academy of Sciences, Beijing 100083, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
ACS Appl Mater Interfaces. 2022 May 11;14(18):21232-21241. doi: 10.1021/acsami.2c03636. Epub 2022 Apr 29.
The high-quality semipolar (112̅2) AlGaN epitaxial films have been obtained on m-plane sapphire by metal-organic chemical vapor deposition. X-ray rocking curve measurements show the full-width at half-maximums of semipolar (112̅2)-oriented AlGaN films are 0.357° and 0.531° along [112̅3̅] and [11̅00], respectively. The fabricated semipolar AlGaN metal-semiconductor-metal solar-blind ultraviolet (UV) photodetector (PD) exhibits a high responsivity of 1842 A/W. The fast response and reliability of the UV PD are ensured via fast switching with a rise and decay time of 90 ms and 53(720) ms, respectively. The UV PD exhibits a significant reduction in the dark current, that is, from 100 μA to 780 fA at 10 V, using a simple wet chemical etching to modify the surface properties of materials. The photo-to-dark-current ratio value of the etched UV PD reaches 4 orders of magnitude higher than the unetched UV PD under 270 nm illumination. These are attributed to the fact that KOH wet etching assists in eliminating the surface states and reconstructing the surface oxides. This work might provide a new potential for the development of solar-blind UV PDs with high performance.
通过金属有机化学气相沉积法在m面蓝宝石上获得了高质量的半极性（112̅2）AlGaN外延薄膜。X射线摇摆曲线测量表明，半极性（112̅2）取向的AlGaN薄膜沿[112̅3̅]和[11̅00]方向的半高宽分别为0.357°和0.531°。制备的半极性AlGaN金属-半导体-金属日盲紫外（UV）光电探测器（PD）表现出1842 A/W的高响应度。通过分别具有90 ms上升时间和53（720）ms衰减时间的快速开关，确保了UV PD的快速响应和可靠性。使用简单的湿化学蚀刻来改变材料的表面性质，UV PD的暗电流显著降低，即在10 V时从100 μA降至780 fA。在270 nm光照下，蚀刻后的UV PD的光电流与暗电流比值比未蚀刻的UV PD高出4个数量级。这些归因于KOH湿蚀刻有助于消除表面态并重构表面氧化物。这项工作可能为高性能日盲UV PD的发展提供新的潜力。
