Electron Beam Irradiation of Gallium Nitride-on-Silicon Betavoltaics Fabricated with a Triple Mesa Etch

TL;DR

This paper presents a novel process for fabricating GaN-on-Si betavoltaic devices using a triple mesa etch, demonstrating promising electrical performance under electron beam irradiation and potential for broader electronic applications.

Contribution

Developed a new triple mesa etch fabrication technique for GaN betavoltaics on silicon, with device testing and simulation showing promising efficiency and design potential.

Findings

Maximum open-circuit voltage of 412 mV

Power conversion efficiency of 6.6%

Potential for versatile device fabrication

Abstract

A process for growing gallium nitride (GaN) vertical p-i-n homojunctions on (111) silicon (Si) substrates using metalorganic chemical vapor deposition (MOCVD) was developed, and a triple mesa etch technique was used to fabricate efficient betavoltaic energy converters. Monte Carlo simulation platform CASINO was used to model beta radiation penetration into GaN to aid device design. The resulting devices were tested under irradiation from a scanning electron microscope (SEM) electron beam (e-beam) tuned to imitate the energies of the 63Ni beta emission spectrum. Based on current-voltage (I-V) measurements taken under e-beam illumination, a maximum open-circuit voltage of 412 mV and a maximum short-circuit current density of 407 nA/cm2 were measured. A high fill factor (FF) of 0.77 and power conversion efficiency of 6.6% were obtained. Additionally, the proposed triple mesa etch technique used to create these betavoltaics has potential for further use in fabricating many types of electronic devices using a wide variety of material platforms.