Density of states of a two-dimensional electron gas measured by high-resolution photoelectron spectroscopy

We present high energy-resolution photoemission measurements of the spectra l density at the discrete quantized electronic levels of a two-dimensional (2D) electron gas. The dynamical 2D electron gas has been obtained by gener ating a strong accumulation layer at the (110) surface of narrow-gap III-V semiconductors. Exploitation of a number of cases generating band bending ( metallic chains or clusters, atomic structure, defects) demonstrates the ge nerality of 2D electron gas formation at charge-accumulated semiconductor s urfaces. A self-consistent solution of the Poisson and Schrodinger equation s gives the potential well shape, the sub-band energy level position and th e accumulated charge density, in excellent agreement with the present exper imental data. (C) 1999 Published by Elsevier Science Ltd. All rights reserv ed.