Abstract:

The n-type 1.5% Ge doped WOx thin film was deposited on Al/p-type Si wafer using the Physical Vapour Deposition (PVD) technique and Al/Si/WOx(%1.5Ge) p-n junction was fabricated. The surface properties of the thin film layer were examined by scanning electron microscopy (SEM) and it was generally observed that the layer had a smooth structure with various size particles grown on surface. In addition, the elemental composition of the thin film was examined by Energy dispersive X-ray spectroscopy (EDS), and it was observed that all detected elements showed a homogeneous distribution at the rates of 96.4% W, 1.5% Ge and 2.2% O. In order to examine the electrical properties of the fabricated heterojunction, Ag rectifier contacts were grown on the active layer surface by the PVD method. As a result, I-V measurements of Al/p-Si/WOx(1.5%Ge)/Ag heterojunction was performed under dark and various light intensities in the potential range of ±4V. Thus, diode parameters such as series resistance, diode ideality factor, barrier height and reverse saturation current were determined by using different methods. It is observed that the series resistance is between 70-10Ω, the diode ideality factor is between 14.1 and 3.9, the barrier height is between 0.54-0.15eV and the reverse saturation current is between 1.34x10-4 A-1.1x10-3 A. The series resistance of the fabricated diode decreased with the increase of the light intensity, and the diode approached the ideal. In addition, the ten times increase in reverse saturation current with light intensity indicates that the fabricated heterojunction exhibits typical photodiode behaviour.

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