ANOMALOUS QUENCHING OF PHOTOEMISSION FROM BULK STATES BY DEPOSITION OF CS ON INAS(100)

The effect of angle-resolved valence-hand photoelectron spectra from adsorption of small amounts of Cs on InAs(100)4 X 2 has been studied. It is shown that a bulk interband transition is totally quenched at a coverage of Cs that leaves the 4 X 2 reconstruction practically intact. The surface order was monitored by low-energy electron diffraction and photoemission from surface states. A shift of the surface Fermi level to well above the conduction-band minimum is also observed. It is proposed that the resulting development of a two-dimensional electron gas at the surface affects the bulk states probed in photoemission.