ON THE ELECTRICAL-PROPERTIES, THE INTERFACIAL REACTIVITY AND THE THERMAL-STABILITY OF COSI2/P-INP, TISI2/P-INP, CO/P-INP AND TI/P-INP SCHOTTKY BARRIERS

In this paper the Schottky barrier heights of CoSi2/- and TiSi2/p-InP contacts are determined to be 0.93 and 0.95 eV respectively. These values are clearly different from those of Co/- and Ti/p-InP contacts, for which a value of 0.85 eV is found. Auger depth profiling shows that the silicide contacts have an abrupt, unreactive interface, whereas for the other contacts the complementary concentration of Co (or Ti) and In at the interface, lead us to suppose that phosphide formation occurs even at room temperature. After a 450°C anneal, a distinct phosphide layer can be observed next to the expelling of In towards the surface during the phosphidation. The stability during heat treatments was investigated for the different contacts. The Co and Ti contacts only withstood up to a range of 250-350°C, due to enhanced phosphidation at the interface and oxidation at the surface. Higher values were found for the silicide contacts, namely 450°C for TiSi2 and even 550°C for CoSi2. For these contacts, it was found that after annealing at higher temperature In (and some P) were present at the outer surface. We assumed that these elements left the InP substrate, where VIn vacancies were created which behave as acceptors and produce thermionic field emission. © 1990.