Ohmic performance comparison for Ti/Ni/Au and Ti/Pt/Au on InAs/graded InGaAs/GaAs layers

Metallization systems of Ti/Ni/Au and Ti/Pt/Au were deposited onto InAs/gra ded InGaAs/GaAs epitaxial layers grown on GaAs substrate. Both of them exhi bit good nonalloyed specific contact resistance of 1.0 x 10(-6) and 3.0 x 1 0(-6) Ohm cm(2) for Ti/Pt/Au and Ti/Ni/Au metallization systems, respective ly. However, the thermal stability can be achieved at least up to 350 degre es C for Ti/Pt/Au metallization system, while the Ti/Ni/Au metallization ca n only thermally stabilize at 250 degrees C. The degradation of the specifi c contact resistance at high annealing temperature is attributed to the ind uced decomposition of InAs and graded InGaAs layers. Rutherford backscatter ing spectroscopy spectra and Auger electron spectroscopy depth profile were used to study the physical mechanism. (C) 2000 Elsevier Science S.A. All r ights reserved.