Electrical and optical properties of boron-doped ZnO thin films for solar cells grown by metalorganic chemical vapor deposition

The highly conductive and textured ZnO films have been grown by metalorganic chemical vapor deposition using diethylzinc and H2O as reactant gases. The B2H6 gas has also been successfully used as an n-type dopant gas to obtain highly conductive ZnO with a sheet resistivity for 2-μm-thick film as low as 10 Ω/⧠ at the very low temperature of 150 °C. It was found that the crystal orientation and grain structure change with B2H6 flow rate. The decreasing of the film transmittance due to the free-carrier absorption in the wavelength region above 1000 nm was observed and it seems that the impurity scattering was the dominant interaction during this process. The shift of the absorption edge due to band filling was also observed as the B2H6 flow rate was increased.