Surface and Bulk Contributions to Ultraviolet Photoemission Spectra of Silicon

Photoemission measurements have been made on clean silicon surfaces having (111) 7 7, (111) 2 1, and (100) 2 1 low-energy electron diffraction patterns. An approximate separation of the data into surface and bulk components yields a bulk distribution which is in better agreement with the theoretical density of states than previous results. The surface distribution for the (111) 7 7 surface contains five distinct features.