Electron injection-induced effects in Si-doped β-Ga2O3

Sushrut Modak,Fan Ren,Leonid Chernyak,Stephen J Pearton,Jiancheng Yang,Jonathan Lee,Igor Lubomirsky,Sergey Khodorov

doi:10.1063/1.5079730

Abstract

The impact of electron injection, using 10 keV beam of a Scanning Electron Microscope, on minority carrier transport in Si-doped β-Ga2O3 was studied for temperatures ranging from room to 120°C. In-situ Electron Beam-Induced Current technique was employed to determine the diffusion length of minority holes as a function of temperature and duration of electron injection. The experiments revealed a pronounced elongation of hole diffusion length with increasing duration of injection. The activation energy, associated with the electron injection-induced elongation of the diffusion length, was determined at ∼ 74 meV and matches the previous independent studies. It was additionally discovered that an increase of the diffusion length in the regions affected by electron injection is accompanied by a simultaneous decrease of cathodoluminescence intensity. Both effects were attributed to increasing non-equilibrium hole lifetime in the valence band of β-Ga2O3 semiconductor.

Highlights

Wide bandgap semiconductors such as GaN and ZnO are important for a number of applications ranging from flame detection and high temperature electronics to solar-blind ultraviolet detectors and sensors for use in extreme environmental conditions.1–3 An emerging semiconductor with a direct bandgap of 4.69 eV, Ga2O3 has become an attractive candidate for radiation applications in terms of its superior stability over GaN and ZnO.1,4–9So far, the main limiting factor in Ga2O3 technology is related to difficulties of p-type conductivity realization.7,9–11 Previous studies indicate that holes in β-Ga2O3 have characteristics of low dispersion, high effective mass and high density of states
This paper demonstrates the impact of electron injection on minority carrier transport in Si-doped β-Ga2O3
A typical Electron Beam-Induced Current (EBIC) line-scan taken at room temperature is shown in Fig. 1, where the current is shown as a function of beam position measured from the edge of the Schottky contact

Summary

INTRODUCTION

Wide bandgap semiconductors such as GaN and ZnO are important for a number of applications ranging from flame detection and high temperature electronics to solar-blind ultraviolet detectors and sensors for use in extreme environmental conditions. An emerging semiconductor with a direct bandgap of 4.69 eV (ultra-wide bandgap), Ga2O3 has become an attractive candidate for radiation applications in terms of its superior stability over GaN and ZnO.. Previous studies indicate that holes in β-Ga2O3 have characteristics of low dispersion, high effective mass and high density of states. This results in formation of weak polarons (or localized holes), trapped by lattice distortions in the vicinity.. Recent studies on diffusion length of minority holes in n-type β-Ga2O3 report the value ∼ 400 nm at room temperature.. Like in the case of ZnO and GaN, the issue of short diffusion length for minority carriers exists in β-Ga2O3 and limits its possible applications in bipolar devices. This study testifies that: 1) one can engineer minority carrier diffusion length with electron injection (increase it several times); 2) the non-equilibrium holes, generated due to electron beam, are not self-trapped and contribute profoundly to the Electron Beam-Induced Current

EXPERIMENTAL

RESULTS

DISCUSSION AND CONCLUSIONS