MgGaO Solar-Blind Photodetectors With Ultralow Dark-Current Prepared by Adjusting MgO Cycle Ratio

Abstract

Gallium oxide 2O $(Ga_{{3}}\text {)}$ is regarded as a promising material for solar-blind photodetectors owing to its wide bandgap properties. However, oxygen vacancy defects within the material limit its further enhancement of optoelectronic performance. Current research primarily focuses on doping modifications to improve the properties of Ga2O3, because the doping concentration significantly influences the performance of films. In this work, magnesium (Mg) doping was introduced to enhance the optoelectronic properties of Ga2O3 films. Mg-doped Ga2O3 (MgGaO) films were fabricated using plasma-enhanced atomic layer deposition (PEALD) through adjusting the magnesium oxide (MgO) cycle ratio. The structural, chemical, morphological, and optical properties of MgGaO films were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and ultraviolet-visible spectroscopy. The results indicate that as the MgO cycle ratio increases, the crystallinity and surface roughness of MgGaO films improve, and the optical bandgap increases from 4.84 to 5.91 eV. The oxygen vacancy content in the films decreases initially but increases at higher MgO cycle ratios. Additionally, the films with different MgO cycle ratios were applied to fabricate solar-blind photodetectors. The photodetector demonstrated the best performance at an MgO cycle ratio of 5%, exhibiting a dark current as low as $4.90\times 10^{-{15}}$ A, an ultrahigh photocurrent-to-dark current ratio of $9.70\times 10^{{6}}$ , and rise/decay times of 74.7/45.7 ms, with the highest responsivity of 13.2 mA/W in the 200–280 nm range. This study demonstrates that MgGaO films hold great potential application in high-performance solar-blind photodetectors.