Two-dimensional x-ray photoelectron diffraction measurements by a retarding field-type analyzer

Abstract

Two-dimensional x-ray photoelectron diffraction (XPED) patterns of Ga3d and As3d photoelectrons from GaAs(001) were rapidly measured by using a retarding field-type electron energy analyzer and a synchrotron radiation x-ray source. In the raw images of photoelectrons obtained with this analyzer, clear XPED patterns were not observed, for most of the contrast was caused by moiré patterns of the four-grid electrodes. In order to obtain net XPED contrast, it is necessary to remove such instrumental functions. For this purpose, three techniques were applied: First, to perform pixel-by-pixel division between an image from a single-crystal sample and one from a polycrystalline sample. Second, to restore the XPED pattern by arithmetic treatments from two images measured before and after sample rotation. Third, to perform pixel-by-pixel division between an image from the crystal-state sample and one from the amorphous state, where the samples of two different states were obtained from the same sample before and after annealing without changing its position. In the case of GaAs, clear XPED patterns of Ga3d and As3d were obtained only by the third technique. The resultant patterns agreed well with calculated XPED patterns.