METALLIZATIONS OF INP BASED ON TRANSITION-METALS

Single element Ni and Cr metallizations to low doped n- and p-Inl have been investigated to clarify how they affect electrical performance o f advanced multilayer metallizations for ohmic contact and Schottky di ode applications. It was found that the Ni and Cr contacts to n-InP sh ow unstable ohmic behaviour at all annealing temperatures (300-500 deg rees C), and that Ni and Cr metallizations to p-InP show diode behavio ur. The electrical behaviour of the contacts were compared to phase fo rmation paths of Ni-In-P and Cr-In-P ternary systems. From this it was found that amorphous ternary phases form first by interdiffusion of C r and Ni into the InP crystal. Subsequently, at higher annealing tempe ratures, crystallization and eventually phase separation determines th e electrical properties of the contacts. After annealing at 500 degree s C the Cr diodes to p-InP are almost ideal, as deduced from barrier h eight measurements using a combination of I-V and C-V methods. This in dicates that the metallization forms a two-layer structure with Cr-P p hases lying above pure In. The Ni diodes to p-InP annealed at 500 degr ees C, on the other hand, are not ideal, indicating that Ni-In and Ni- (In)-P phases in parallel are determining the electrical properties of the diode.