Graphene/GaN ultraviolet photodetector performance regulated by a HfO2 insulating layer

Abstract

The ultraviolet (UV) photodetector is a device that converts optical signals into electrical signals and is the core component of all UV detection systems. A UV photodetector based on a combination of Graphene (Gr, 2D) and GaN (3D) has been reported in this work. High-performance ultra-shallow van der Waals heterojunction ultraviolet photodetectors were realized in this work, and the effects of an interfacial HfO2 tunneling layer on their photoelectric characteristics were investigated in detail. The findings of the study indicated that interfacial defects were effectively repaired by depositing a thin insulating tunneling layer of HfO2 between GaN and Gr using the ALD method with a 3 nm thick layer of HfO2 providing the best results. It was also found that the high-speed carriers underwent ion collision during the tunneling process, resulting in multiplication of the photocurrent. Consequently, the device exhibited a high R value of 318.6 A/W and a large D* value of 1.046 × 1015 Jones under an illuminated power density of 5 μW/cm2 with an external bias voltage of −2 V. The results of this study further validated the application of interfacial engineering technology, while providing insights into the carrier transport mechanism between 2D and 3D materials for the fabrication of high-performance optoelectronic devices.