We present a new analytical potential fluctuations model for the interpretation of current/voltage and capacitance/voltage measurements on spatially inhomogeneous Schottky contacts. A new evaluation schema of current and capacitance barriers permits a quantitative analysis of spatially distributed Schottky barriers. In addition, our analysis shows also that the ideality coefficient n of abrupt Schottky contacts reflects the deformation of the barrier distribution under applied bias; a general temperature dependence for the ideality n is predicted. Our model offers a solution for the so-called T0 problem. Not only our own measurements on PtSi/Si diodes, but also previously published ideality data for Schottky diodes on Si, GaAs, and InP agree with our theory.

We investigate the temperature dependence of Schottky barrier heights on silicon. The analysis of a large variety of polycrystalline diodes shows that the temperature coefficient of the barrier height depends on the chemical nature of the metal. This observation is in contradiction with models suggesting Fermi-level pinning at the center of the semiconductor’s indirect band gap. From the analysis of epitaxial NiSi2/Si Schottky contacts, we conclude that there is a direct influence of interface crystallography on both the barrier height and its temperature dependence. Finally, we present some new results on the pressure coefficient of barrier heights. Pressure and temperature coefficients of polycrystalline Schottky contacts are correlated similarly to the pressure and temperature coefficients of the band gap.

Electronic properties of Schottky diodes depend sensitively on spatial inhomogeneities of the metal/semiconductor interface. We find that, contrary to previous theories for low-frequency noise, the electronic properties of Schottky contacts cannot be understood if one neglects spatial fluctuations of the Schottky barrier height. Our systematic investigation of several silicide/silicon diodes yields as an empirical law that excess noise increases drastically when the standard deviation σs of the spatial distribution of Schottky barrier heights exceeds the critical threshold value of 2kT.

Subbandgap absorption of chemical-vapor-deposition diamond films, with nitrogen contents varying from 10 to 132 ppm has been explored by the constant-photoconductivity method ͑CPM͒, photothermal-deflection spectroscopy ͑PDS͒ and electron spin resonance ͑ESR͒. The spectra measured by PDS increase monotonically and are structureless with increasing photon energies indicating absorption due to amorphous carbon and graphite. The CPM data show distinct features, with absorption bands at hϭ1.6, 4.0, and 4.7 eV in the nominally undoped film, and 2.4 and 4.7 eV in nitrogen-rich layers respectively. The CPM spectra of the doped films are comparable to photoconductivity data of synthetic Ib diamond. The defect densities involved increase with increasing nitrogen content. From ESR, a vacancy-related defect density (gϭ2.0028) is deduced. Paramagnetic nitrogen (gϭ2.0024) can be detected in the high-quality CVD layer or by illuminating the nitrogenrich samples with photon energies larger than the band gap.

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