β-Ga2O3 van der Waals p-n homojunction

Abstract

The van der Waals (vdW) p-n junctions are crucial to develop multifunctional and high-performance electronic and optoelectronic devices. The asymmetric doping effect in wide-bandgap (WBG) semiconductors poses a fundamental obstacle for fabricating the vdW p-n homojunction and impedes the development of full WBG semiconductors-based bipolar devices. In this study, we demonstrate the β-Ga2O3 vdW p-n homojunctions with 2.0 nm-thick vdW gap, 2.6 eV built-in potential and 1.5 μm-wide depletion region, via combining quasi-two-dimensional n-type β-Ga2O3 nanosheets with p-type β-Ga2O3 films. Various tunneling transports including direct tunneling, Fowler-Nordheim tunneling, and exciton-assisted tunnelling are observed and explored in detail. The β-Ga2O3 vdW p-n homojunction diodes possess high forward current density (3.0 × 10−3 A/cm2), extremely-low reverse leakage current density (3.0 × 10−9 A/cm2), high rectification ratio (106 under dark and 107 under illumination), high photoresponsivity (13.4 A/W) and detectivity (9.38 × 1013 Jones) at 10 V bias under 250 nm illumination, and narrowband detection for the deep-ultraviolet solar-blind spectral region. This work lays the foundation for β-Ga2O3 homogeneous bipolar vdW devices and paves the way to advance the next-generation electronic and optoelectronic multifunctional devices based on the vdW integration.