Photoemission Investigation of the 2D Electron Gas Created At the InAs(110) Surface

On InAs(110) surfaces a downward band bending (BB) was produced either by cleavage defects or by adsorption of very small amounts of Cs atoms. As a consequence the Fermi level was moved high into the conduction band, resulting in the formation of a two-dimensional electron channel (2D-EC). Electron emission arising from this channel was detected by angle-resolved photoelectron spectroscopy near the [Formula: see text] points of the first and second surface Brillouin zones. We present a detailed investigation of the corresponding photoemission characteristics using tunable low energy synchrotron radiation light. We find in particular that the photoemission intensity depends drastically on the photon energy. This effect is interpreted as resulting from the quantization of the 2D electron gas in the direction normal to the surface; it is directly linked to the electron density sampled (i.e. the depth probed) beneath the top surface.