Heterojunction Devices Fabricated from Sprayed -Type GaO, Combined with Sputtered -Type NiO and CuO.

This work reports on the properties of heterojunctions consisting of -type GaO layers, deposited using ultrasonic spray pyrolysis at high temperature from water-based solution, combined with -type NiO and CuO counterparts, deposited by radio frequency and reactive, direct-current magnetron sputtering, respectively. After a comprehensive investigation of the properties of the single layers, the fabricated junctions on indium tin oxide (ITO)-coated glass showed high rectification, with an open circuit voltage of 940 mV for GaO/CuO and 220 mV for GaO/NiO under simulated solar illumination. This demonstrates in praxis the favorable band alignment between the sprayed GaO and CuO, with small conduction band offset, and the large offsets anticipated for both energy bands in the case of GaO/NiO. Large differences in the ideality factors between the two types of heterojunctions were observed, suggestive of distinctive properties of the heterointerface. Further, it is shown that the interface between the high-temperature-deposited GaO and the ITO contact does not impede electron transport, opening new possibilities for the design of solar cell and optoelectronic device architectures.