DEPOSITION OF BORON DOPED ZINC-OXIDE FILMS AND THEIR ELECTRICAL AND OPTICAL-PROPERTIES

Boron doped zinc oxide films were deposited by atmospheric pressure chemical vapor deposition in a laminar flow reactor from diethyl zinc, tert-butanol, and diborane in the temperature range from 300 to 420-degrees-C. When the deposition temperature was above 320-degrees-C, both doped and undoped films have highly oriented crystallites with their c-axes perpendicular to the substrate plane. Films deposited from 0.07% diethyl zinc and 2.4% tert-butanol have electron densities from 3.5 to 5.5 x 10(20) conductivities from 250 to 2500-OMEGA--1 cm-1, and mobilities from 2.5 to 35 cm/V-s, depending on dopant concentration, film thickness, and deposition temperature. Optical measurements show that the maximum infrared reflectance of the doped films is close to 90%, compared to about 20% for undoped films. Visible absorption and conductivity were found to increase with thickness. The ratio of conductivity to visible absorption coefficient for doped films was from 0.1 to 1.1-OMEGA--1. The bandgap of the film changes from 3.3 to 3.7 eV when the film is doped with 0.012% diborane.