Enhanced performance of solar-blind photodetector of hexagonal boron nitride with bottom-contact electrodes

Naifu Zhang,Wenjun Wang,Yanpeng Song,Kaiyao Zhou

doi:10.1063/5.0010182

Abstract

A deep ultraviolet photodetector has wide applications in both military and civil fields, such as the missile early warning system, transparent wireless communication, environmental monitoring, and so on. Because of its wide bandgap, hexagonal boron nitride (h-BN) has been envisioned to be a promising material for deep ultraviolet photodetectors. In this work, we have synthesized high-quality h-BN crystals using the flux growth method at atmospheric pressure. Based on the thin-layered h-BN prepared by mechanical exfoliation, two types of solar-blind photodetectors, with either top-contact or bottom-contact electrodes, were fabricated. It is found that the device with bottom-contact electrodes exhibits excellent performance in the specific detectivity exceeding 3.68 × 108 Jones (cm Hz1/2 W−1) at 215 nm. Moreover, the photodetectors have a cutoff wavelength at about 270 nm, which demonstrates that the device can be an ideal candidate for a solar-blind photodetector.

Highlights

Hexagonal boron nitride (h-BN) is a promising material for the fabrication of deep ultraviolet (DUV) photodetectors because of its prominent physical properties, such as wide bandgap, large thermal conductivity, high band-edge absorption coefficient, and low dielectric constant.1,2 up to now, the reported h-BN based DUV photodetectors are rare and their UV responses are not as good as expected, except the one sealed in a vacuum cavity exhibiting amazing detecting performance in 160 nm vacuum ultraviolet wavelength.3 This means the device was measured under a vacuum ambient with a pressure of about 5 × 10−5 Torr, corresponding to an application scenario of space detection.the DUV devices working in atmospheric environment are necessary and convenient to practical applications
Photodetectors was obtained either by mechanical exfoliation of various thick h-BN films prepared by the flux growth method3 or by direct growth on a supporting substrate by the chemical vapor deposition (CVD) technique4,5 or pulsed laser plasma deposition (PLPD) technique
In this article, the h-BN based MSM structural DUV photodetectors with both top-contact and bottom-contact electrodes with the same device sizes were designed and comparatively studied, where the adopted thin-layered h-BN materials were mechanically exfoliated from thick h-BN single crystals grown by the flux growth method at atmospheric pressure

Summary

INTRODUCTION

Hexagonal boron nitride (h-BN) is a promising material for the fabrication of deep ultraviolet (DUV) photodetectors because of its prominent physical properties, such as wide bandgap, large thermal conductivity, high band-edge absorption coefficient, and low dielectric constant. up to now, the reported h-BN based DUV photodetectors are rare and their UV responses are not as good as expected, except the one sealed in a vacuum cavity exhibiting amazing detecting performance in 160 nm vacuum ultraviolet wavelength. This means the device was measured under a vacuum ambient with a pressure of about 5 × 10−5 Torr, corresponding to an application scenario of space detection. The thin-layered h-BN adopted for the fabrication of DUV photodetectors was obtained either by mechanical exfoliation of various thick h-BN films prepared by the flux growth method or by direct growth on a supporting substrate by the chemical vapor deposition (CVD) technique or pulsed laser plasma deposition (PLPD) technique.6–9 The quality of these h-BN materials does not meet the requirements for high performance DUV photoconductors due to the existence of defects or single crystal size. In this article, the h-BN based MSM structural DUV photodetectors with both top-contact and bottom-contact electrodes with the same device sizes were designed and comparatively studied, where the adopted thin-layered h-BN materials were mechanically exfoliated from thick h-BN single crystals grown by the flux growth method at atmospheric pressure. The detailed results concerning characterization on the thin-layered h-BN materials and related device performance are given below, and the mechanisms governing the DUV photodetector performance are analyzed and discussed

EXPERIMENTAL SECTION

RESULTS AND DISCUSSION

CONCLUSION