PREPARATION OF CONDUCTIVE ZNO-AL FILMS BY A FACING TARGET SYSTEM WITHA STRONG MAGNETIC-FIELD

Transparent conductive ZnO:A1 films were prepared in Ar gas by a plana r magnetron sputtering system with facing targets, where strong intern al magnets were contained in target holders to confine the plasma betw een the targets. A film resistivity of 4 x 10(-4) Ohm cm was attained at a substrate temperature of 200 degrees C. However, the film resisti vity increased with increasing substrate temperature, due to a decreas e of the carrier concentration. The reason for this phenomenon was the decrease of Zn donors in the film as native donors or an increase of Zn defects. When excess Zn atoms were supplied during film growth, a l ow resistivity of 2 x 10(-4) Ohm cm was obtained even at a substrate t emperature of 250 degrees C.