Effects of sputtered buffer layer on the characteristics of ZnO:Al films grown on glass substrates using high-temperature H2O generated by a catalytic reaction

The improvement in the quality of ZnO:Al films grown on glass substrates was investigated using a sputtered buffer layer inserted between a glass substrate and a ZnO:Al CVD film. ZnO:Al layers were grown at 773 K using dimethylzinc (DMZn), trimethylaluminum (TMAl), and high-temperature H2O generated by a catalytic reaction as zinc, aluminum, and oxygen sources, respectively. The electron mobility increased by approximately 20 cm2 V−1 s−1 with the use of a buffer layer with a thickness of approximately 40 nm. In addition, the optical transmittance in the wavelength range of 380-600 nm increased with the insertion of the buffer layer. For the growth of ZnO films on a sputtered buffer layer, the average surface roughness was reduced, and as a result the fluctuation in crystal orientation along the c-axis became smaller than that of the film grown directly on the glass substrate by the proposed CVD. This resulted in improvements in the optical transmittance and electron mobility of the ZnO:Al films.