ROLES OF TOP AND FIRST NI-LAYERS IN THE IMPROVEMENT OF ELECTRICAL PROPERTY AND SURFACE-MORPHOLOGY IN NI AL/NI/N-INP CONTACTS/

The formation of wide band gap material (AlP) in Al/n-InP contacts lea ds to an enhancement of Schottky barrier height (E-SBH) upon rapid the rmal annealing (RTA), but the alloying reaction was irregular. The add ition of 5 nm first- and/or 14 nm top-Ni layers gives an excellent imp rovement in the electrical uniformity as well as the surface morpholog y for Al/n-InP contacts. The Ni first layer provides the formation of AlP and Ni2P by the solid-phase reaction between Ni and InP at rather low temperatures (around 450 degrees C) and results in the uniform int erface. The addition of the Ni top layer further gives the interfacial uniformity thanks to prevention of irregular alloying.