In situ Observation of Formation Process of Negative Electron Affinity Surface of GaAs by Surface Photo-Absorption

Abstract

We have used surface photo-absorption (SPA) to investigate the formation of negative electron affinity (NEA) surfaces on p-GaAs during the Yo-Yo method, under an alternating supply of Cs and O2. The SPA spectra showed that the surface during the first Cs step was different from those in the following Cs and O2 steps. This suggests that the surface structure did not change after the initial surface was formed, indicating that there could be two Cs adsorption sites on the GaAs surface, which is different from previously proposed models.

Nonlocal and local mechanisms of cesium-induced chemisorption of oxygen on a p-GaAs(Cs, O) surface

“…The existing technologies of the formation of (Cs, O) layers cannot affect the degree of ordering of the (Cs, O) dipoles and, therefore, cannot satisfy completely the increasing demands on photocathodes. Search for the ways of their improvement continues [6] but has not yet provided the desired results. In order to find the means of affecting the degree of ordering of the (Cs, O) layers, in this work we studied the relations between the probability of the Cs induced chemisorption (η ox ) of molecular oxygen on the p GaAs(Cs, O) surface and the composition of the (Cs, O) layer.…”