Optical and electrical properties of p-type transparent conducting Cu-Al-O thin films prepared by plasma enhanced chemical vapor deposition

Abstract

The growth of p-type transparent conducting oxide thin film has attracted much attention due to its potential in making novel transparent p-n junctions for device applications. In this work, the transparent conducting Cu-Al-O thin films were prepared by plasma enhanced chemical vapor deposition using metal organic precursors of Cu(acac)2 and Al(acac)3 (acac=acetylacetonate) in a mole ratio of 1:1 sublimated at 150°C. The metal organic vapor was carried into a reaction chamber by argon gas. Reactive oxygen gas was introduced into the chamber via another gas inlet. Substrate temperatures were varied over the range 630-800°C and the processing pressure was kept constant at about 0.15 Torr. Seebeck effect measurements revealed that these films were p-type semiconductors. X-ray diffraction results showed that Cu-Al-O films were amorphous. The resistivity mechanism of the low resistivity of Cu-Al-O films is probably governed by the scattering of the dominant hole-carriers by impurities. The film conductivity increased with increasing growth temperature. The films prepared at 800°C with a resistivity of 5.0 Ω·cm and transparency of over 60% in the visible light region were achieved. © 2001 Elsevier Science B.V. All rights reserved.