Plasma-enhanced atomic layer deposition of N-doped GaO thin film for bandgap modulation

Bandgap modulation is extremely important for optoelectronic and electronic devices. However, compare with II-VI and III-V compound semiconductors, the ultrawide bandgap semiconductor Ga2O3 (III-VI) faces a tough obstacle of bandgap modulation. Herein, we have prepared a N-doped GaO thin film on Si substrate through a plasma-enhanced atomic layer deposition (PEALD) method. The as-deposited GaO:N layer exhibits amorphous nature with thickness of 8.4 nm. The bandgap of the as-deposited GaO:N layer is adjusted to 4.31 eV, which is 0.49 eV smaller than the bandgap of pure Ga2O3. In addition, the photoluminescence (PL) spectra from five randomly selected points of the film layer indicate the uniformly distribution of N concentration. Subsequently, the energy band diagram of the as-deposited GaO:N layer is determined by the X-ray photoelectron spectroscopy (XPS), in which the Fermi energy level locates 0.81 eV below the conduction band minimum (CBM) and 3.5 eV above the valence band maximum (VBM). Our study raises a promising strategy for modulating the bandgap of Ga2O3, which provides potential applications in spectrum adjustable photodetector and high electron mobility transistor.