Ultra-high photoresponse with superiorly sensitive metal-insulator- semiconductor (MIS) structured diodes for UV photodetector application

摘要

Here, we fabricated highly sensitive metal-insulator-semiconductor (MIS) type diodes with positive photo-response by introducing a polycrystalline Ce-WO3 composite thin films as an interfacial layer (IL) between the metal (Cu) and semiconductor (p-Si). Ce-WO3 films were successfully grown on a quartz substrate through JNSP technique with 0, 4, 8 and 12 wt% of Ce on an optimized substrate temperature of 400 degrees C. Polycrystalline Ce-WO3 films with mono-phase of monoclinic crystal structure were observed in XRD analysis, in which the mean crystallite size of the films were found to dwindle and their corresponding lattice parameters improved with Ce concentration. Randomly arranged rectangular shaped nanoplate-like surface morphology was observed through FESEM. From AFM study, the observed surface roughness of the films was found to be varying between 183 and 116 nm. Incorporation of Ce atoms in WO3 matrix facilitated better optical absorption and minimized E-g values which was studied using UV-vis spectrum. Current-voltage (I-V) characteristics exhibit highest sigma(dc) with low rho and E-a values for higher concentration of Ce. For Cu/Ce-WO3/p-Si type diodes, as the light intensity of the diodes increased from 0 to 130 mW/cm(2) their corresponding ideality factor (n) was found to decrease. Moreover, significant photodiode parameters like P-S, R, QE (%) and D* enhanced with Ce and in particular the MIS diode fabricated with its 12 wt% showed better results in which a remarkable responsivity of 20.61 mA/W was recorded.