Dual-band and dual-mode ultraviolet photodetection characterizations of Ga<sub>2</sub>O<sub>3</sub>/Al<sub>0.1</sub>Ga<sub>0.9</sub>N homo-type heterojunction
Authors: Li Lei , Zhi Yu-Song , Zhang Mao-Lin , Liu Zeng , Zhang Shao-Hui , Ma Wan-Yu , Xu Qiang , Shen Gao-Hui , Wang Xia , Guo Yu-Feng , Tang Wei-Hua ,   Innovation Center for Gallium Oxide Semiconductor (IC-GAO), College of Integrated Circuit Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China,   National and Local Joint Engineering Laboratory for RF Integration and Micro-Assembly Technologies, Nanjing University of Posts and Telecommunications, Nanjing 210023, China,   Institute of Microscale Optoelectronics, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China,   China Academy of Launch Vehicle Technology, Beijing 100076, China,   Department of Electrical Engineering and Automation, Shanxi Institute of Technology, Yangquan 045000, China
Published: October 2022

The deep-ultraviolet (DUV) photodetectors (PDs) have important applications in lots of fields. Thus, developing self-powered DUV PDs and excavating the inherent mechanism seem seriously crucial to achieving further actual applications. The construction of heterojunction can lead to many desired characteristics in optoelectronic devices. In the field of DUV photodetection, Ga<sub>2</sub>O<sub>3</sub> has been a popular subject for constructing DUV PDs. So, it is necessary to develop self-powered Ga<sub>2</sub>O<sub>3</sub>-based DUV PDs through fabricating its heterogeneous structure. Therefore, in this work, the Ga<sub>2</sub>O<sub>3</sub>/Al<sub>0.1</sub>Ga<sub>0.9</sub>N heterojunction DUV PD is fabricated and discussed, which can achieve 254 and 365 nm DUV light photodetection. At positive voltages and negative voltages, the heterojunction PD can operate in a photoconductive mode or a depletion mode, respectively. In view of the PD performance, it displays decent dark current and DUV photoresponses. At voltage of 5 and –5 V, under 254 nm DUV light illumination, the photoresponsivity (<i>R</i>) is 2.09 and 66.32 mA/W, respectively, while under 365 nm DUV light illumination, <i>R</i> is 0.22 and 34.75 mA/W, respectively. In addition, under the built-in electric field (<i>E</i><sub>built-in</sub>), <i>R</i> is 0.13 and 0.01 mA/W for 254 nm and 365 nm DUV light illumination, respectively. In all, the fabricated heterojunction PD displays promising prospects in the coming next-generation semiconductor photodetection technology. The results in this work indicate the potential of Ga<sub>2</sub>O<sub>3</sub>/Al<sub>0.1</sub>Ga<sub>0.9</sub>N heterojunction with high performance DUV photodetection. Furthermore, except for the characterizations of the materials and photodetector, in the end of this paper, the operating mechanism of the dual-band dual-mode heterojunction PD is analyzed through its heterogeneous energy-band diagram. It is concluded that the illustrated dual-band dual-mode Ga<sub>2</sub>O<sub>3</sub>/Al<sub>0.1</sub>Ga<sub>0.9</sub>N heterojunction can be sensitive to UVA waveband and UVC waveband in the electromagnetic spectrum, extending its photodetection region. And, the dual-mode (photoconductive mode and depletion mode) photodetection indicates two kinds of carrier transports in one PD, which can be attributed to the successful construction of the N-N tomo-type Ga<sub>2</sub>O<sub>3</sub>/Al<sub>0.1</sub>Ga<sub>0.9</sub>N heterojunction.