A new LEED Instrument for Quantitative Spot Profile Analysis

TL;DR

This paper introduces a novel SPA-LEED instrument capable of detailed electron diffraction spot profile analysis, enabling both visual inspection and quantitative intensity measurements for surface structure characterization.

Contribution

The paper presents a new SPA-LEED instrument with enhanced scanning and measurement capabilities, demonstrating improved resolution and quantitative analysis of surface diffraction patterns.

Findings

Achieved a transfer width of up to 200 nm.

Demonstrated the instrument's effectiveness on Si 111 7x7 surface.

Performed initial high-resolution measurements on Pb/Cu 111.

Abstract

A new instrument for spot profile analysis of electron diffraction - SPA-LEED - has been set up. The instrument works either with a transparent phosphor screen for visual inspection of the pattern or in its main mode with a channeltron for the measurement of the intensity. The diffraction pattern is recorded with a fixed channeltron position by scanning the beam over the channeltron aperture using two sets of electrostatic deflection plates. The scanning range covers about 30{\deg}. The intensity may vary over five orders of magnitude. The SPA-LEED system was checked with the Si 111 7 x 7 surface. A full width at half maximum of 0.3% of the normal reflex distance corresponding to a transfer width of 110 nm is reproducibly obtained. Under optimum conditions the transfer width rose up to about 200 nm. Initial high resolution measurements have been performed on the system Pb on Cu 111. The results demonstrate the possibilities of the new instrument for qualitative and quantitative analysis.