On the basis of numerical analysis, a model of the intimate metal-semiconductor Schottky-barrier (SB) contact is proposed. According to this model, the Fermi-level pinning at the contact is due to high density of electron surface states in equilibrium with the metal, whereas the IV characteristic distortions (deviation from ideality) are due to a continuous (and/or discrete) spectrum of the energy-and coordinate distributed (in the general case) nearsurface states in equilibrium with the semiconductor. This model amplifies the Bardeen model for actual SB contacts that is limited by the assumption of the presence of an intermediate insulating layer. However, the assumption is not necessarily fulfilled for the contacts manufactured using currently available technologies.

The model of an ideal (without an intermediate layer and electron surface states) metal-semiconductor Schottkybarrier contact is numerically analyzed with allowance for the effect of image-force barrier-height lowering. It is shown that the nonlinear dependence of barrier height on the bias voltage inherent in this contact causes not only the deviation of the current-voltage (I-V) characteristic from an ideal one but also the so-called "low-temperature anomaly" − an increase in the I-V-characteristic ideality factor n and a decrease in the barrier height ϕ bm measured from the saturation current as the temperature is decreased. A more exact equation for the I-V characteristic of the ideal contact is theoretically substantiated using parameters n and ϕ bm in a wide temperature range.

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A possibility of a more simple and exact representation of the current-voltage (I-V) characteristic of a tunnel metal-semiconductor contact is investigated. Analysis is made on the basis of the approach proposed earlier, according to which the behaviour of the (I-V) characteristics of the Schottky-barrier contacts at low temperatures depends on the nonlinear dependence of the true (or effective for a tunnel contact) barrier height on the bias voltage. A simple equation for the (I-V) characteristic of the tunnel contact is theoretically substantiated using measurable parameters -the ideality factor n and barrier height ϕ bm where the quantity ϕ bn ≡ nϕ bm plays the role of a barrier height. The calculation shows that this quantity is very close to the true barrier height of the tunnel contact (with allowance for the effect of image force) in wide current, temperature, and impurity-concentration ranges.