CHARGE-TRANSFER ACROSS THE AS/SI(100)-2X1 INTERFACE

A high-performance Auger spectrometer has been used to separate the bulk and interface contributions to the Auger spectra of the As/Si(100) interface. Combining these results with measurements of the photoelectron spectra of core levels shows that the Auger-parameter shifts between atoms at the interface and in the bulk elements are -0.64 +/- 0.04 eV for As and 0.68 +/- 0.04 eV for Si. The Auger-parameter shifts are analyzed in terms of recent theoretical models that indicate that there is a small charge transfer of approximately 0.2e from Si to As at the interface.