Metal-Semiconductor Contacts: Surface Morphology and BEEM,
Abstract
Ballistic Electron Emission Spectroscopy (BEEM) is a promising new variant of STM spectroscopy that allows the determination of Schottky barrier heights with high lateral resolution for relatively thick (approx. 100 angstrom) metal overlayers. The technique encompasses the injection of electrons or holes with an STM, which then reach the interface without scattering (ballistically). At the interface they will be reflected unless sufficient bias is applied between the tunneling tip and the metal overlayer to overcome the Schottky barrier height (sec Fig. 1). Once the electrons reach the conduction band of the semiconductor they will be detected as a collector current Ic. Representative Ic vs Vt, where Vt is the tip-to-metal bias, are shown in Fig. 2 for Ag and Au films on GaP(110). The Schottky barrier height is associated with the voltage threshold Vo, beyond which a current can be detected. Because of the soft turn on of Ic, Vo, is poorly defined unless the appropriate shape of the I-V curve is known from theoretical considerations.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 22, 1992
- Accession Number
- ADP007924
Entities
People
- A. Samsavar
- M. Prietsch
- R. Ludeke
Organizations
- IBM Thomas J. Watson Research Center