ELECTRONIC PHYSIC ON A METAL-SEMICONDUCTOR INTERFACE

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Metal-Si Schottky contacts have been made by using various metals in order to investigate the dependence of typical diode parameters, such as the barrier height and the effective Richardson constant, on a film thickness of the metal electrode. In any contact with a metal-electrode film below 400 <Ang> thickness, the Schottky barrier height evidently varies with the film thickness. The effective Richardson constant obtained by a photoelectrical measurement shows different values, depending upon the choice of metal, and also shows a metal-thickness dependence, contrary to the generally accepted theory for metal-semiconductor contacts. In particular, the effective Richardson constant in a sample made by rf sputtering shows a much larger film-thickness dependence than that in a sample by vacuum evaporation. Furthermore, for the purpose of investigating the cause of the change in the effective Richardson constant with the metal-film thickness, a 1000-<Ang>-thick Pt film has been deposited by rf sputtering onto Si substrates which have been heated to various temperatures between room temperature and 500゜C. The barrier height and the effective Richardson constant for these Pt-Si contacts have been investigated photoelectrically. As a result, it has been found that the dependences of the barrier height and the Richardson constant on the thickness of a sputtered Pt film quite agree with the dependences of those on the temperature of a Si substrate.