Temperature-dependent pinning at the Al/n-GaAs(110) interface

It is shown that at the Al/n-GaAs(110) interface grown in ultrahigh vacuum at −80 °C the Fermi level remains unpinned at least up to a 3 monolayer coverage. In contrast, at room temperature the pinning near midgap is established after a deposition of approximately 1 monolayer of Al. The low-temperature behavior is correlated with the growth of a more uniform overlayer which inhibits cluster and defect formation. This result provides a critical test of models of Schottky barrier formation.