Correlation of Electrical Properties with Structure Imaging of Semiconductor Interfaces

High resolution electron microscopy (HREM) is recognised as a powerful technique for thedetermination of atomic structures at crystal defects and interfaces. The application ofHREM to the study of insulator/semiconductor and metal/semiconductor interfaces is of particular technological interest. Correlation of electrical properties withinterface structure has been performed, taking advantage of the resolution available in the JEOL 4000EX. Images are usually obtained in a projection, however in the JEOL 4000EX (point-to point resolution <1.7A). we have imaged semiconductor interfaces in the <100=direction using the (220) planes of 1.92A spacing revealing all atomic columns in silicon, permitting “structure images” of interfaces to be obtained. Two types of interface have been studied at <1.9A resolution. The roughness of the important crystalline Si/amorphousSiO2 interface observed in implanted buried oxide layers and after wet and dry oxidation of silicon is relevant for the correlation of carrier mobilities with interface structure. Analysis of both the NiSi2/Si(100) and AI/AIGaAs(100) crystal/crystal interfaces where a periodic structure is observed in the plane of the interface allows the use of rigid shift measurements and multislice image calculations to determine an atomistic model. The influence of the NiSi2/Si interface structure on the Schottky barrier height is discussed.