Forward current-voltage characteristics of Schottky barriers on n-type silicon

Abstract

An analysis of the forward I–V data of the Schottky barriers formed by Au, Ni and Cr on n-type Si, and of two commercially available Schottky barrier diodes (Fairchild's FH-1100 and Hewlett-Packard's HP-2900) is presented. When the fringing high electric fields at the edge of the diodes are eliminated by using guard rings or mesa structures, their I–V behavior is given by I = I s [ exp{ qV k(T + T 0) } − 1] , where To is a constant. When the fringing high electric fields are not eliminated, thermionic-field (T-F) emission is observed, which increases T 0 at low temperatures. Activation energy plots of ln( I s T 2 ) versus I T are not linear for guard ring or non-guard ring diodes implying that the barrier height, φ ms, varies with temperature. Plots of ln( I s T 2 ) versus I (T + T 0 ) are found to be linear for either kind of diode, which give effective barrier heights, σ mso, independent of temperature. For non-guard ring diodes, T 0 varied with temperature and it was calculated at each temperature; for guard ring diodes, T 0 was approximately a constant with respect to temperature. Therefore, the saturation current I s is given by I s = A ∗T 2 exp{− φ MSO k(T + T 0) } . A model employing temperature dependence of the barrier height, φ ms, in the simple Schottky theory is given which explains, qualitatively, T 0 and φ mso.