Ballistic Electron Emission Microscopy Studies of Electron Scattering in Gold/gallium Arsenide Schottky Diodes Damaged by Focused Ion Beam Implantation.
Ballistic Electron Emission Microscopy (BEEM) is a technique for measuring lateral variations in interface transmission properties, primarily in metal-semiconductor systems. BEEM's capability to study these variations with nanometer scale resolution makes it advantageous over other methods which average interface characteristics over large areas. In this work, BEEM has been used to study Au/GaAs Schottky diodes and modifications that result from Focused Ion Beam (FIB) implantation. Dramatic reductions in interface transmission are observed in regions damaged by the implant. This is believed to be a consequence of implantation-induced scattering. As expected, greater attenuation is seen at higher implantation doses. Traditional models of BEEM transport address scattering losses with a simple overall attenuation coefficient used as a fitting parameter. In this work, a model is developed which quantifies these scattering losses by including quantum mechanical transmission at the interface, optical phonon scattering in the semiconductor, implantation induced scattering in the semiconductor, and finally scattering from native and induced defects in the Au layer. This model is then compared with data from damaged and undamaged regions. By using scattering lengths within the range given in literature, scattering losses can be appropriately modeled for the undamaged spectra. For the damaged spectra, qualitative agreement between the model and data is seen. However, quantitative agreement requires the use of scattering lengths shorter than those in the literature and higher implantation-induced defect densities than predicted by the model.
- Pub Date:
- January 1995
- Physics: Condensed Matter; Engineering: Materials Science