FRACTAL BEHAVIOR OF THE SURFACE OF IN-SITU HEAT-TREATED METAL-INP CONTACTS

The heat treatment of metallised compound semiconductors results mater ial diffusion and evaporation, called volatile component loss. In situ SEM and mass spectrometric study showed, that surface pattern has fra ctal character at heat treatment temperatures, where the volatile comp onent loss has maximum value. The so-called fractal dimension or scali ng factor of self-similarity (D) was evaluated for Au/lnP (D = 1.57 +/ - 0.01), Pd/InP (D = 1.75 +/- 0.01) and Au/Pd/InP contacts. The compar ison of SEI and BEI images suggested that the geometrical surface patt erns, resulted by the balling-up phenomenon, and the pattern, which po ssible describes the phase inhomogeneity on the same contact, can be c haracterised by different values of the fractal dimension. In the case of the studied Au/Pd/InP contact, D was 1.56 +/- 0.02 for balling up and D was 1.84 +/- 0.01 for phase distribution. (C) 1998 Elsevier Scie nce S.A.