Production and comparative study of ZnO films obtained by magnetron sputtering, MOCVD and electrochemical deposition

Abstract

It was found that the morphology, electrical and luminescence properties of ZnO layers obtained by Magnetron sputtering, MOCVD and Electrochemical deposition can be controlled by technological parameters such as the ratio of argon-to-oxygen gases in the gas flow as well as the temperature of the substrate with the MOCVD and magnetron sputtering method, or by the composition and the temperature of solutions with the ECHD method. The low temperature PL spectra of nanorods grown by MOCVD is dominated by emission related to neutral donor bound excitons (D0X), while the emission from nanodots is dominated by a band related to donor-acceptor DA recombination. The origin of the DA PL band is discussed. The low temperature PL spectrum of ZnO bulk layers in the near-bandgap spectral range is dominated by a superposition of D0X related bands. The smooth films produced with a high Ar/O ratio during magnetron sputtering exhibit weak luminescence suggesting an amorphous nature of the film. Annealing of samples in air during 30 min at 450 oC after the deposition process leads to increasing luminescence intensity due to the crystallization. An n-ZnO/p-Si photodiode structure was produced by MOCVD, and its electrical characteristics were investigated in details.