Tunable Electrical and Optical Properties of Nickel Oxide (NiOx) Thin Films for Fully Transparent NiOx-Ga2O3 p-n Junction Diodes

One of the major limitations of oxide semi-conductors technology is the lack of proper p-type materials to enable devices such as pn junctions, light-emitting diodes, and photodetectors. This limitation has resulted in an increased research focus on these materials. In this work, p-type NiOx thin films with tunable optical and electrical properties as well as its dependence with oxygen pressure during pulsed laser deposition are demonstrated. The control of NiOx films resistivity ranged from similar to 10(9) to similar to 10(2) Omega cm, showing a p-type behavior with E-g tuning from 3.4 to 3.9 eV. Chemical composition and the resulting band diagrams are also discussed. The all-oxide NiOx-Ga2O3 pn junction showed very low leakage current, an ideality factor of similar to 2, 10(5) on/off ratio, and 0.6 V built-in potential. Its J-V temperature dependence is also analyzed. C-V measurements demonstrate diodes with a carrier concentration of 10(15) cm(-3) for the Ga2O3 layer, which is fully depleted. These results show a stable, promising diode, attractive for future photoelectronic devices.