Enhanced Performance of a Visible Light Detector Made with Quasi-Free-Standing Graphene on SiC.

Xiaomeng Li,Zhiyuan Zuo,Xiufang Chen,Xiangang Xu,Xiaobo Hu

doi:10.3390/ma12193227

Abstract

The excellent optoelectronic properties of graphene give it great potential for applications in optical detection. Among the graphenes obtained through many synthetic methods, epitaxial graphene obtained by thermal decomposition on silicon carbide has remarkable advantages for preparing photodetectors. In this research, epitaxial graphene has been successfully prepared on a silicon surface (0001) of semi-insulating 4H-SiC substrate with a size of 10 mm × 10 mm and epitaxial graphene has been converted to quasi-free-standing graphene by hydrogen passivation. Two metal-graphene-metal photodetectors were fabricated using the two types of graphenes above and the photo-absorption properties of detectors have been investigated under 650-nm laser illumination with different illumination powers. From a comparison of the performances between the two detectors, it was found that a photodetector fabricated with quasi-free-standing graphene shows enhanced performance under a light power of 0.018 mW. Responsivity and external quantum efficiency reach maxima of 5.11 A/W and 9.74%, respectively. This dramatic improvement is mainly due to the disappearance of the buffer layer in epitaxial graphene, providing a new method to achieve optimization of graphene-based opto-electrical devices.

Highlights

Photodetectors, part of the technical foundation of our information society, are widely used in communications, imaging, sensing and other applications [1]
This can be confirmed by the scanning electron microscope (SEM) image (Figure S2 in the Supplementary Materials) of the two samples that the signal of the quasi-free-standing graphene (QFSG) sample (Figure S2b) with larger work function in the SEM image is weaker than the epitaxial graphene (EG) sample (Figure S2a)
In order to further verify the effect of hydrogen passivation on the buffer layer, we measured the two epitaxial graphenes (EG and QFSG) with X-ray photoelectron spectroscopy (XPS)

Summary

Introduction

Photodetectors, part of the technical foundation of our information society, are widely used in communications, imaging, sensing and other applications [1]. With different materials and structures, have been reported in recent years [2,3,4,5]. Due to the increasing demand for high-performance miniature photodetectors in recent years, low-dimensional materials, because of their excellent performance, have received extensive attention and photodetectors with thin-film heterojunction structures have been studied in depth [6,7,8,9,10]. In these photodetectors, the built-in field at the interface of the heterojunction structures plays a very important role.

Methods

Results

Conclusion