High resolution transmission electron microscopy to study very thin crystalline layers buried at an amorphous-crystalline interface

Structure characterisation of interfaces is a field of widespread applicati on of high resolution transmission electron microscopy for its very high sp atial resolution. Specimen thickness and electron optical condition have a deep influence on the high resolution electron transmission microscopy imag e contrast. Hence, in many cases, the real structure of the sample can be u nderstood from experimental images only by comparison with the relevant sim ulation. Moreover, the understanding of the contrast variation of a few Ang strom at an interface is a task in which even the use of simulation could n ot produce an unequivocal solution of the experimental result. In this paper high resolution transmission electron microscopy image simula tions show that two monolayers of crystalline material buried at an amorpho us-crystalline interface can be successfully revealed and interpreted. The simulated images reproduce the experimental results as obtained from the Al /Si-As/n-GaAs (001) heterostructure. (C) 2000 Elsevier Science Ltd. All rig hts reserved.