Surface pattern formation and the volatile component loss of heat treated metallisations of InP

Abstract

Palladium based metal systems can be used to make ohmic contacts to A/sup III/B/sup V/ compound semiconductors. A covering layer of gold is advantageous from the point of view of bonding as well. Gold palladium layers were studied on InP substrates. Samples were annealed in the vacuum chamber of a scanning electron microscope (SEM) and the volatile component loss (phosphorus) was monitored by a quadrupole mass spectrometer. The changes of the surface morphology were studied using the SEM images. It means that the change of surface morphology and the volatile component loss were monitored simultaneously. In the case of Pd/A/sup III/B/sup V/ samples a single characteristic peak due to the interaction taking place between the metallization and the substrate was observed on the volatile component loss vs. temperature curve. In this temperature range characteristic pattern formation can be detected. This surface morphology shows fractal behaviour. It is supposed that the giant volatile component loss originating from the interaction between the metallization and the substrate can be described using percolation theory.