Experimental results examining various models of Schottky barrier formation on GaAs

Abstract

The mechanism of Schottky barrier formation on GaAs and other semiconductors seems to be getting more, rather than less, controversial. Therefore, it is important to examine new data as it becomes available. Four types of data will be mentioned. The emphasis will be on (1) the metal–GaAs chemical reaction products at the interface and their correlation (or lack thereof) with barrier heights and (2) the lack of evidence for discontinuity in Schottky barrier height as one goes from photoemission spectroscopy (PES) pinning results (thickness of order 1–1000 Å metal films). Also mentioned are (3) changes in barrier height for Al, Au, and Ag on diodes annealed up to 500 °C and (4) the effect on barrier height of growing ∼20 Å of native oxide on the GaAs before depositing a 1000-Å metal layer. These data will be presented for discussion and evaluated in terms of the various models of Schottky barrier formation now under discussion which appear most consistent with the unified defect model.