Compositional Studies of Semiconductor Alloys by Bright Field Electron Microscope Imaging of Wedged Crystals

Abstract

ABSTRACTThe use of a cleaved 90 degree wedge as a cross section sample for transmission electron microscopy allows the composition of III/V semiconductor alloys to be measured by studying the thickness fringes of the on-axis [010] bright field image. The effect is explained in terms of the incident electron Bloch states and is illustrated by reference to GaAs/AlGaAs. The technique has an accuracy of about 5% and a spatial resolution of a few Å. The range of materials that can be analysed in this way is discussed.