p-Type copper aluminum oxide thin films for gas-sensing applications

Abstract In this study we deposited new, ternary thin films of copper aluminum oxide with p -type and n -type behavior using RF magnetron sputtering for use as chemical gas sensors. p -Type materials are known to be good catalysts and can be combined with the well-known n -type materials for chemiresistive sensors application. Copper aluminum oxide in the delafossite phase CuAlO 2 is a ternary oxide that has generated interest as a transparent p -type conducting material, while in the spinel phase CuAl 2 O 4 is known to be n -type. We demonstrated that thin films of copper aluminum oxide with the proper resistance can be successfully applied as p - and n -type resistive gas sensors for ozone detection. We have studied the sputtering deposition conditions from a CuAlO 2 sintered target by changing the substrate temperature in inert Ar atmosphere. In addition, post-deposition annealing in O 2 atmospheres was also tested. XRD, SEM and Raman investigations were used to characterize the thin films. Selected films with mixed phases of CuAlO 2 , CuAl 2 O 4 and CuO were tested for gas sensing as resistive chemical sensors, showing promising results with ozone, acetone and ethanol.

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