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

One of the major limitations of oxide semiconductors 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 NiO 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 NiO films resistivity ranged from ∼10 to ∼10 Ω cm, showing a p-type behavior with E tuning from 3.4 to 3.9 eV. Chemical composition and the resulting band diagrams are also discussed. The all-oxide NiO -GaO pn junction showed very low leakage current, an ideality factor of ∼2, 10 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 cm for the GaO layer, which is fully depleted. These results show a stable, promising diode, attractive for future photoelectronic devices.