Reflected electron energy loss microscopy (REELM) studies of metals, semiconductors and insulators

Abstract

The potential of reflected electron energy loss microscopy (REELM) are tested in surface and interface studies of metals, semiconductors and insulators. We present spectroscopic analyses of loss signals occurring at ∼5–30 eV of the elastic peak, and microscopic analyses based on the same signals performed via spot mode, as well as via linescanning and imaging modes. Materials investigated include a UHV cleaved InSb surface, InP/SiO 2 and GaAs/Au systems, W tips for use in an STM microscope, a ZrO 2 single crystal, and an archaeological bronze covered with a thick patina. Advantages and shortcomings of REELM are outlined against the diagnostic value of parallel results obtained by scanning Auger microscopy (SAM) techniques. Although comparatively poor focussing powers preclude the attainment of high spatial resolution, and spectral interference problems may hinder the chemical characterization of multi-phase materials, REELM features unique capabilities. Among others, these include a chemical contrast that is much superior to that of SAM, the possibility of characterizing the coverage distribution of adlayer surface species, as well as of investigating the microchemistry of insulators’ surfaces. The first application of REELM in the analysis of archaeological materials is presented.