Numerical simulations are presented of the potential distribution and current transport associated with metal-semiconductor (MS) contacts in which the Schottky barrier height (SBH) varies spatially. It is shown that the current across the MS contact may be greatly influenced by the existence of SBH inhomogeneity. Numerical simulations indicate that regions of low SBH are often pinched-off when the size of these regions is less than the average depletion width. Saddle points in the potential contours in close proximity to the low-SBH regions, which are shown to vary with the dimension and magnitude of the inhomogeneity as well as with bias, essentially determine the electron transport across the low-SBH regions. It is these dependences of the saddle point which give rise to various abnormal behaviors frequently observed from SBH experiments, such as ideality factors greater than unity, various temperature dependences of the ideality factor, including the T0 anomaly, and reverse characteristics which are strongly bias-dependent. The results of these numerical simulations are shown to support the predictions of a recently developed analytic theory of SBH inhomogeneity.

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The paper presents a general approach to numerically simulate the noise behavior of bipolar solid-state electron devices through a physics-based multidimensional device model. The proposed technique accounts for noise sources due to carrier velocity and population fluctuations. The power and correlation spectra of the external current or voltage fluctuations are evaluated through a Green's function, linear perturbation theory equivalent to the classical Impedance Field Method for noise analysis and its generalizations. The numerical implementation of the method is performed through an efficient technique, which allows noise analysis to be carried out with negligible overhead with respect to the small-signal simulation. Some case studies are analyzed in order to compare the present approach with theoretical results from the classical noise theory of pn junctions and bipolar transistors.

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