Fabrication and characterization of p-Si/n-In2O3 and p-Si/n-ITO junction diodes for optoelectronic device applications

Abstract

Octahedral novel indium tin oxide (ITO) films were fabricated on glass substrates. The dopant material tin (Sn) was added at different concentration like 0, 5, 10, 15 weight percentage (wt.%) with indium oxide precursor and the synthesis was done by spray pyrolysis technique. XRD studies revealed proper doping of tin in indium oxide crystal lattice structure. The surface morphology of ITO films confirmed the octahedral structure of crystallites formed and the variation in size of the microstructures with doping concentration. The bonding states of indium and tin with oxygen and composition of ITO films were inspected through XPS. The average roughness of films varied from 26.65 to 139.08 nm. The optical properties studied from UV-VIS studies showed a sharp increase in bandgap from undoped to 5 wt.% Sn doped indium oxide films followed by slight decrease in values with the increase in doping concentration. The photoluminescence excitation of ITO films showed a rapid fall in the peak intensity values due to the quenching of oxygen vacancies and a slight blue shift in emission confirms the doping of tin indium oxide. The resistivity values tremendously decrease with increase in doping concentration, that is tin doping improves conduction which was observed using two probe method. The fabricated p-Si/n-ITO junction diode shows that the ITO is degenerated semiconductor and the photo response is exhibited with a high ideality factor of 8.98 in dark and 6.46 in visible light exposed conditions respectively.