The effects of surface relaxation and ion thinning on delta-doped semiconductor cross-sections

摘要

The measured distributions of As delta-doped layers within InP are found to vary depending on the technique used to prepare the TEM sample foil. Comparison of conventional cross-sectional specimens prepared by ion milling with cleaved-wedge samples is made using high resolution electron microscopy and Fresnel analysis. The observed width of the delta-doped layer is influenced by surface amorphisation due to the ion beam damage and surface relaxation due to the thin specimen. The effect of free surface relaxation is found to dominate HREM images acquired from cross-sectional specimens, although surface amorphisation should also be considered when data is analysed quantitatively.