Influence of metal (M = Cd, In, and Sn) dopants on the properties of spin-coated WO3 thin films and fabrication of temperature-dependent heterojunction diodes

Abstract

Metal-doped tungsten trioxide (M = Cd, In, and Sn:WO3) thin films were prepared using sol–gel spin-coating and their structural, optical, electrical properties were studied for the fabrication of p–n heterojunction diode. X-ray diffraction (XRD) analysis revealed that Cd, In, and Sn dopants have a strong influence on the lattice parameters and defect factor without making any changes in the structure. Scanning electron microscope (SEM) images reflect that the dopants have a strong impact on the surface morphologies of the WO3 thin film. The UV–visible analysis shows a high optical transmittance (∼82%) and variation in the bandgap was also obtained. The dc electrical conductivity (σdc) indicates that the band conduction mechanism is predominant in the pure and doped M:WO3 thin films. Current density–voltage (J–V) characteristics of WO3/p-Si, Cd:WO3/p-Si, In:WO3/p-Si, and Sn:WO3/p-Si diodes were measured under dark and illumination conditions. In which, the Sn:WO3/p-Si diode exhibits better performance with good ideality factor (n = 2.6) and barrier height (ФB = 0.90) values for under illumination. Most importantly, the J–V–T characteristics of all the fabricated diodes were analyzed with different temperatures (303–423 K).