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ABSTRACT: CuAlO <sub>x</sub> thin films were prepared at three substrate temperatures ( T<sub>S</sub>=60 , 300, and 600 ° C ) and two oxygen partial pressures ( P<sub> O <sub>2</sub></sub>=0.5 and 2 mTorr) via dc reactive magnetron sputtering from Cu–Al 50–50 at. % alloy targets and subsequent annealing. As-deposited films with P<sub> O <sub>2</sub></sub>=0.5 mTorr were oxygen deficient; although the delafossite structure formed upon annealing, electrical properties were poor. Films deposited with P<sub> O <sub>2</sub></sub>=2 mTorr transformed into the delafossite structure and exhibited p -type conductivity after annealing under N <sub>2</sub> at temperatures T<sub>A</sub>≥750 ° C . Conductivity generally increased with increasing T<sub>S</sub> and decreasing T<sub>A</sub> . A special case of P<sub> O <sub>2</sub></sub>=2 mTorr and low T<sub>S</sub> (60 ° C ) resulted in a partially crystalline oxide phase that transformed into the delafossite structure at T<sub>A</sub>=700 ° C and yielded the highest conductivity of 1.8 S <font face='roman' ||
'>cm <sup>-1</sup> . In general, a T<sub>A</sub> near the phase formation boundary led to an increase in conductivity. Low-temperature hydrothermal annealing was also investigated and shown to produce mixed phase films exhibiting the delafossite structure along with CuO, AlOOH, and Al <sub>2</in-
-
f> O <sub>3</sub> .
Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 02/2011; · 1.25 Impact Factor
