PALLADIUM BASED CONTACTS TO GaAs AND InP

Abstract

Au(85nm)/Pd(55nm) and Pd(55nm) metallizations were deposited on GaAs(lOO) and InP(100) substrates. The samples were heat treated in a scanning electron microscope (SEM) equipped with a quadrupole mass spectrometer. The simultaneous observation of the volatile component loss (in situ) by Evolved Gas Analysis (EGA) and the change in surface morphology by SEM during the heart treatment using a heating rate of 30°C/min were carried out. The interaction of the metallization with compound semiconductor substrates was observed after the heat treatment by transmission electron microscopy (TEM) using samples prepared by cross-sectional technique. In the course of the present work a large volatile component (arsenic and phosphorus) loss was observed for the samples coated by single layer metallization (at 410° C for Pd/GaAs and at 580°C for Pd/InP) and two peaks were registered in the case of Au/Pd metallization. In the latter case the cause of the second evaporation peak is the interaction between diffused gold and compound semiconductor. The SEM images of the surfaces demonstrate a significant change of the surface morphology at the singularities of the EGA curves. The grains grown into the semiconductors are shown by the cross-sectional images of the heat treated samples.