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DPG

Regensburg 1998 – scientific programme

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HL: Halbleiterphysik

HL 24: Poster II

HL 24.22: Poster

Wednesday, March 25, 1998, 10:30–19:00, A

The origin of the integral barrier height in inhomogeneous Schottky contacts: A ballistic electron emission microscopy (BEEM) study — •Alexander Olbrich, Johann Vancea, Franz Kreupl, and Horst Hoffmann — University of Regensburg, D-93040 Regensburg, Germany

In this work ballistic electron emission microscopy was used to probe on nanometer scale the local Schottky barrier height (SBH) in metal-semiconductor (MS) contacts with an intentionally inhomogeneously prepared metallization. Schottky barrier maps of heterogeneous
Au/Co/GaAs47P33(100)-Schottky contacts show areas with different barrier heights, which can be correlated to different metallizations (Au or Co) at the interface. Co/GaAsP and Au/GaAsP yield a SBH of 1030 meV and 1180 meV,respectively. Transitions between areas of different SBH are in excellent agreement with the theory of the potential pinch-off effect in inhomogeneous MS contacts. The lateral extension and density of the SBH inhomogenities was systematically varied by changing the preparation parameter, i.e. the Co film thickness and deposition temperature. Treating the local SBH distributions measured with BEEM in terms of a parallel conduction model yields an integral SBH for each set of parameter. These calculated SBH‘s are in very good agreement with the corresponding macroscopic SBH’s obtained from conventional I-V. The strong influence of the low SBH on the electron transport across the interface and therefore on the macroscopic SBH is discussed in detail.

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