Browsing by Author "Kashinje, Peter Stanlaus"

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    Investigation of Kanthal-silicon junction devices
    (University of Dar es Salaam, 1978) Kashinje, Peter Stanlaus
    This work describes experimental investigations of natal semiconductor junctions consisting of films of the alloy kanthal deposited on noncerystalline silicon. The interest in this stemma from the possible application in hybrid circuits.Kanthal consists mainly of Iron and Chromium. The films of Kanthal have been deposited on a and p-type Silicon in the (iii) orientation by RF sputtering a Kanthal target. The Silicon has been trended chemically and some of the wafers were sputter-etched before depositing the films. This description includes a discussion of basic physical concepts and the theory of semiconductors and metal semiconductor junctions in order to facilitate the comparison with experimental data. The experimental procedures followed in the investigations have been described in details. These include; Current-Voltage characteristics, forward and reveres bias. Reverse bias activation plots at temperatures higher than room temperature. The differential capacitance of a reverse biased Metal-Semiconductor junction. Measurement have been and using a Boonton 750 Bridge. The photo-electric method has also been utilized. Fowler plots have been obtained where-ever it was found convenient. This is achieved through the use of a rather sophisticated double monochromatic and signal processing done with the use of lock in techniques. Fundamental analysis of film composition was done using Rutherford backscattering techniques. Data processing was have good consistency of composition, the composition of the Kanthal films on our diodes had nearly 70% Iron (Fe) and 25% chromium (Cr) compared to 70.6% Fe and 24.1% Cr composition of parent target. The barrier heights obtained by the various techniques were as follows. The hole barrier was obtained by the current-voltage characteristics as Bh=0.68 Ev for non-sputter etched wafers and by the photo-electric method an Bh=0.63ev. the capacitance-voltage method gave Bh=0.67eV. Sputter-etched samples gave slightly lower value of Bh (see chapter iv). The electron barrier Bh was found to be generally much lower than Bh, and as such was determined through activation plots only. For non-sputter etched samples Bh=0.43Ev on a average and sputter-etched samples gave nearly the same value of c/Bh. Annealing of the samples had the effect of raising c/Bh and lowering c/Bh in both sputter-etched and non-sputter etched samples. These results suggest that we can make good diodes by sputtering (RF) Kanthal to pSi. substance using a sputtering power of 400w/7min. with the same specifications we can obtain good chmic contact to nSi.