A fabrication technique is described for the formation of metal-semiconductor contacts, with minimum contamination, on a production basis. Contacts of this type have been formed by cleavage in high vacuum in a stream of metal atoms which has very limited application or by normal evaporation which produces contaminated contacts. The basic structure consists of a layer of epitaxial silicon, on a suitable substrate, on which is deposited a film of molybdenum by the hydrogen reduction of the chloride in the same chamber. The system is adaptable to multiple slice operation. Measurements of switching speed indicate that the reverse recovery times are on the order of 1 nanosecond or less. This very short recovery time is attributed to the high injection efficiency which approaches unity. The high electron injection efficiency reduces the minority carrier concentration in the depletion region thereby reducing trr. Data is presented on both forward and reverse characteristics for diodes fabricated on both epitaxial and bulk silicon with different impurity concentrations. Reverse currents on the order of 10 nanoamps at 10 volts have been observed on epitaxial silicon and forward current densities of 30,000-40,000 amperes per square centimeter, at 1 volt, have also been observed. Data is also presented to show the effect of impurity concentration on barrier height.
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