On the Current-Voltage Characteristic of an Ideal Metal-Semiconductor Schottky-Barrier Contact

Abstract

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.

On the current-voltage characteristic of a tunnel metal-semiconductor Schottky-Barrier contact

“…It should be noted that the dependences of the (I-V) characteristics on the logI (Fig. 3) are qualitatively similar to the bias-voltage dependences used earlier for analyzing other models of contacts [7,8]. However, our dependences are more convenient for analysis, because in reality, the parameters n and ϕ bm are determined at a given current or in a given range of currents rather than at given bias voltages.…”

“…We omit this case from consideration. By analogy with the ideal contact (with allowance for the image-force effect) [7] and real contact (Bardin's model) [8], the forward characteristic of a tunnel contact is written as…”

“…where ϕ b (V) is the effective (in contrast to real [7,8]) barrier height. Since for a tunnel contact we can formally speak about the low-temperature anomaly (see above), the dependence of the ϕ b (V) on the bias voltage is nonlinear (superlinear) [9], and characteristic (5) …”

“…A special feature of tunnel contacts as compared to the non-tunnel ones [7,8] is a very weak current dependence of the ideality factor of the (I-V) characteristic (Fig. 3а), measured barrier height, and quantity ϕ bn ≡ nϕ bm (Fig.…”

“…With allowance for the foregoing similarity, we can show using numerical analysis (this is the objective of this paper) that the (I-V) characteristic of a tunnel contact can be represented in a simple analytic form as for any contact with the low-temperature anomaly [7][8][9] 2 exp exp bn q qV…”