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We have performed ballistic-electron emission microscopy (BEEM) on (Pd,Pt)/(6H,4H)-SiC(0001) Schottky contacts. Schottky barrier heights (SBHs) determined from the BEEM data using the Bell–Kaiser model are 1.27 eV/1.34 eV (Pd/Pt) for 6H- and 1.54 eV/1.58 eV for 4H-SiC. Our measurements also give the first direct evidence of a second conduction band minimum (CBM) on 4H-SiC about 0.14 eV above the overall CBM. Spatial inhomogeneity of SBHs were examined and shown to be no larger than the fitting error due to the system noise. Additionally, enhanced ballistic transmittance was observed over a region intentionally stressed by injecting high kinetic energy (10 eV above EF) hot electrons using BEEM in the Pt/4H-SiC sample.

Effect of annealing charge injection and electron beam irradation of the Si-SiO2 interface barrier heights and on the work function difference in MOS structures AIP Conf.We have used ballistic-electron emission microscopy ͑BEEM͒ to locally inject and microscopically characterize trapped charge in metal-oxide-semiconductor structures made with Pt metal electrodes, moderately thick (ϳ25 nm͒ SiO 2 films and p-type Si substrates. Electrons injected into the oxide conduction band produce a local suppression in the transmitted BEEM current across the oxide. This suppression depends on the voltage V ox applied across the oxide during injection, indicating that its source is within the oxide film, and does not simply result from hot-electron damage at the metal-oxide interface. This suppression is accompanied by a local increase in the BEEM I-V curve threshold voltage, consistent with a build-up of trapped BEEM electrons in the oxide. For a given trapped charge density we find that the threshold varies systematically with V ox applied during I-V curve measurement. We use these variations to make estimates of the trapped charge density and approximate depth in the oxide film, and find them consistent with previous macroscopic observations. We further study the lateral extent of the suppression and the lifetime of this effect. We also measure the height of the Pt-SiO 2 barrier and observe its lowering due to the image force effect.

We report ballistic-electron emission microscopy (BEEM) investigation of Pd, Pt Schottky contacts on 6H-, 4H-SiC, and Pd/15R-SiC. Measured Schottky barrier heights of 6H-and 4H-SiC samples appear spatially uniform up to the fitting error due to noise (0.03-0.04 eV and 0.1-0.2 eV for 6H-and 4H-SiC, respectively). In 4H-SiC, we observed an additional conduction band minimum (CBM) 0.14 eV above the lowest CBM, which provide direct experimental verification of band theoretical calculation results. Additionally, we sometimes observed enhancement in ballistic transmittance over regions intentionally stressed by hot electron injection using BEEM. We also report recent results on Pd/15R-SiC sample indicating a higher CBM ~0.5 eV above the lowest CBM. In Pd/15R-SiC, interesting large variations in BEEM spectra at different locations were observed, possibly suggesting an inhomogeneous metal/semiconductor interface.