Regensburg 1998 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 24: Poster II
HL 24.22: Poster
Mittwoch, 25. März 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.