Composition determination from HREM images of substitutional alloys

摘要: Abstract The relation between the contrast in an HREM image of a substitutional alloy and local composition is studied within framework real-space theory electron scattering. Two algorithms are derived to determine composition: deconvolution convolution. tested on simulated images Al x Ga 1− As, GaAs/AlAs interface As with randomly occupied group III sites. method very sensitive small deviations from linear relationship composition, influence neighbouring columns. more robust convolution works best for defocus values optimizing differences GaAs AlAs images, sample thickness around 10 nm. It estimated that under optimal imaging conditions compositions can be determined separate columns atoms accuracy ±0.10.