Regensburg 1998 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 24: Poster II

HL 24.142: Poster

Mittwoch, 25. März 1998, 10:30–19:00, A

Microscopic-scale lateral inhomogeneities in Schottky barriers — •S. Heun¹, Th. Schmidt¹, J. Slezak¹, J. Diaz¹, K.C. Prince¹, B. Müller², and A. Franciosi² — ¹Sincrotrone Trieste ELETTRA, 34012 Basovizza-Trieste, Italy — ²Laboratorio TASC-INFM, Padriciano 99, 34012 Trieste, Italy

The band alignment across semiconductor heterostructures determines carrier injection and confinement in devices ranging from MESFETs to lasers. The application of such heterostructures in practical devices as well as the predictive capabilities of existing models hinge on the lateral homogeneity of the interfaces. However, surprisingly large lateral inhomogeneities (0.15 eV as observed with 2 µm lateral resolution) in the band alignment have been recently observed in metal/semiconductor junctions by photoemission spectromicroscopy [1].

We measured the Schottky barrier height of Al/Si/GaAs(001) and of Au/ZnSe(001) heterostructures using the SPELEEM (Spectroscopic Photo Emission and Low Energy Electron Microscope) at ELETTRA synchrotron radiation facility. The search for compositional and structural inhomogeneities which correlate with inhomogeneities in the electronic parameters (Schottky barriers) is ideally suited to the potential of this microscope (lateral resolution 22 nm, energy resolution better than 0.5 eV). After annealing the Al/Si/GaAs heterostructure at 500^∘C for 10 min., we find an inhomogeneous As segregation to the surface.

[1] F. Gozzo et al.: Phys. Rev. B 48 (1993) 17163.