Layer structure analysis of Er δ-doped InP by x-ray crystal truncation rod scattering

Abstract

The layer structure and crystal structure of an Er δ-doped layer in InP are analyzed in a one monolayer (ML) level by an x-ray crystal truncation rod (CTR) scattering measurement using synchrotron radiation. The Er δ-doped InP sample is prepared by organometallic vapor phase epitaxy using trimethylindium, tertiarybutylphosphine, and tris(methyl-cyclopentadienyl)erbium as source materials. The analysis is made by comparing the measured CTR spectra and theoretically generated ones assuming four possible crystal structures for the Er δ-doped layers. We reveal that the Er atoms in InP form the rocksalt structure ErP. In the analysis of the crystal structure the x-ray interference plays a vital role. Er distribution in the δ-doped layer is clearly resolved in 1 ML level. It is shown that the Er atoms are well confined in 5 ML(15 Å) thickness. The total amount of Er atoms is 0.171 ML, which is quite close to 0.2 ML obtained by Rutherford backscattering measurement on the same sample.