High spectral response of self-driven GaN-based detectors by controlling the contact barrier height

Xiaojuan Sun,Dabing Li,Hong Jiang,Hang Song,Zhiwei Zhang,Zhiming Li,Yiren Chen,Guoqing Miao

doi:10.1038/srep16819

Abstract

High spectral response of self-driven GaN-based ultraviolet detectors with interdigitated finger geometries were realized using interdigitated Schottky and near-ohmic contacts. Ni/GaN/Cr, Ni/GaN/Ag, and Ni/GaN/Ti/Al detectors were designed with zero bias responsivities proportional to the Schottky barrier difference between the interdigitated contacts of 0.037 A/W, 0.083 A/W, and 0.104 A/W, respectively. Voltage-dependent photocurrent was studied, showing high gain under forward bias. Differences between the electron and hole mobility model and the hole trapping model were considered to be the main photocurrent gain mechanism. These detectors operate in photoconductive mode with large photocurrent gain and depletion mode with high speed, and can extend GaN-based metal-semiconductor-metal detector applications.

Highlights

High responsivity of self-driven GaN-based detectors with interdigitated finger geometries were realized, which is about 0.104 A/W at 0 V bias for Ni/GaN/Ti/Al detector and the quantum efficiency is about 36%
Because the metal work function (W) values for the four kinds of interdigitated contact metals have the sequence of WNi > WCr > WAg > WTi/Al, the falls in the metal work function (Δ W) between the two interdigitated contacts of the three samples are consistent with the sequence Δ WA < Δ WB < Δ WC
It seems that the responsivity of the self-driven GaN-based detectors is dependent on Δ W

Summary

Introduction

High responsivity of self-driven GaN-based detectors with interdigitated finger geometries were realized, which is about 0.104 A/W at 0 V bias for Ni/GaN/Ti/Al detector and the quantum efficiency is about 36%. While the dark currents for all samples showed nearly identical typical Schottky behavior in the reverse voltage region, the I–V curves showed differences in the forward region.

Results

Conclusion