STRUCTURAL AND ELECTRICAL-PROPERTIES OF NI-CU FILMS DEPOSITED ONTO MGO(001) BY DC BIASED PLASMA SPUTTER-DEPOSITION

Ni-Cu alloy films were deposited onto MgO(001) substrates at 230 degre es C by d.c. plasma sputtering at 2.7 kV and 8 mA in pure Ar gas using an Ni-10wt.%Cu alloy target. The deposition time was 15 or 30 min. A d.c. bias voltage V-s ranging from 0 to -140 V was applied to the subs trate during deposition. The structure, composition and electrical pro perties of the films were studied as a function of V-s using cross-sec tional transmission electron microscopy (XTEM) and X-ray photoelectron spectroscopy (XPS), and measurements of the temperature coefficient o f electrical resistance (TCR) from -135 to -15 degrees C. The alloy fi lms, which have the f.c.c. lattice of the components, are monocrystall ine with the relationship Ni-Cu(001)/MgO(001) and Ni-Cu [010]/MgO[010] unless V-sp=-110 V. The Cu content in the films decreases from 8 wt.% to 3 wt.% as V-s increases from 0 to -140 V. The growth rate of the f ilms and the value of TCR eta (eta>0) depend on V-s; the film thicknes s d for the films deposited for 30 min reaches 50+/-1 nm at V-s=0 V an d 74+/-2 nm at V-s=-140 V, while eta for the films deposited for 30 mi n increases appreciably with increasing V-s compared with the films de posited for 15 min, although eta is highest at V-s=-140 V for both cas es.