Diffusion in multilayers, studied by quantitative chemical mapping at the atomic level
Category
Published on
Type
journal-article
Author
Y. Kim and A. Ourmazd
Citation
Kim, Y. & Ourmazd, A., 1990. Diffusion in multilayers, studied by quantitative chemical mapping at the atomic level. Proceedings, annual meeting, Electron Microscopy Society of America, 48(4), pp.354–355. Available at: http://dx.doi.org/10.1017/s0424820100174904.
Abstract
Using chemical lattice imaging in combination with vector pattern recognition, we study diffusion and interdiffusion at single interfaces in mulilayered semiconductors quantitatively with atomic plane resolution. 20 periods of 50Å C-doped GaAs/50Å undoped GaAs/50Å Al0.4Ga0.6As grown by Molecular Beam Epitaxy(MBE) at 600C was examined to study interdiffusiuori across single GaAs/AlGaAs interfaces as a function of temperature (650C to 750C), depth of interface beneath the surface, and doping . After annealing in bulk form, cross-sectional TEM samples were prepared chemically. Chemical lattice images in the <100> zone axis obtained at an accelerating voltage of 400KV with a JEOL 4000-EX high resolution transmission electron microscope were analyzed by a digital pattern recognition method to obtain composition profiles at each interface before and after annealing.Figure 1 is a chemical lattice image of a C:GaAs/AlGaAs interface. The compositional information in the sample is contained in the local patterns that make up such images. The analysis of such chemical images by the pattern recognition yields quantitative composition profiles across single interfaces. The composition profiles shown in Figure 2 refer to a single interface at a depth of 300Å, before and after annealing at 700C for one hr.
