Copper oxide and tin oxide amorphous-thin-film heterojunction diodes obtained via solution-based techniques with increased rectification after rapid thermal annealing treatments

Metal oxide p-n heterojunctions using p-CuO and n-SnO2 amorphous-thin-films, and polycrystalline n+-Cd2SnO4 as transparent conductive oxide, were investigated using sol-gel and metal-organic decomposition solution-based techniques. CuO and SnO2 layers were formed by sintering at low temperature in air. Rectification factors (R) were calculated from J-V measurements, for both types of diodes. The highest R value was obtained for p-CuO/n-SnO2/n+-Cd2SnO4 diodes, which was increased from 102 to 104 after the n-type material (n-SnO2/n+-Cd2SnO4) was subjected to rapid thermal annealing in vacuum, also at a low temperature of 250 °C for 10 min. The ideality factor (n) estimated for these heterostructures suggests active carrier recombination at the material interfaces, due mainly to a major presence of lattice defects. The order of rectification reached in this work encourages for further advances in the fabrication of heterojunction diodes using low cost solution-based techniques.