Interface control for pure ultraviolet electroluminescence from nano-ZnO-based heterojunction devices

• Published in: Science bulletin Vol. 63; no. 1; pp. 38 - 45
• Main Authors: You, Daotong, Xu, Chunxiang, Qin, Feifei, Zhu, Zhu, Manohari, A. Gowri, Xu, Wei, Zhao, Jie, Liu, Wei
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.01.2018
• Subjects: AlN insulator layer; Directly bonding; Interface control; Pure ultraviolet light emitting diode; ZnO nanorods; 设备接口;紫外;异质;连接控制;ZnO;AlN;光电子;LEDs; ZnO nanorods; Interface control; Pure ultraviolet light emitting diode; AlN insulator layer; Directly bonding
• ISSN: 2095-9273; 2095-9281
• DOI: 10.1016/j.scib.2017.12.006

Realization of pure and stable ultraviolet electroluminescence（UV EL） of ZnO light-emitting diode（LED）is still a challenging issue, due to complicated defects of intrinsic ZnO and the corresponding device interfaces. In this paper, we demonstrated a simple ＆ feasible method to fabricate n-ZnO/AlN/p-GaN heterojunctions light-emitting devices. First, the vertically aligned ZnO nanorods（NRs） have been prepared as high quality active layer, and the nanostructured heterojunction LED arrays were constructed by directly bonding ZnO NRs onto AlN-coated p-GaN wafer. By optimizing the AlN layer thickness to be 20 nm, a strong and pure ultraviolet emission located at 387 nm can be observed. The energy band alignment of n-ZnO/AlN（20 nm）/p-Ga N heterojunction LED has been studied by using X-ray photoelectron spectroscopy（XPS）, the valence band offset between AlN and GaN was calculated to be 0.34 eV. On the other side, the conduction band offset（as large as 3.28 eV） between Al N and ZnO can block the flow of electrons from ZnO top-GaN. Thus, electron-hole recombination takes place in the ZnO layer, and a pure UV EL could be observed. Our results provide a significant approach toward future of pure ultraviolet optoelectronic LEDs.