Tailoring nanostructure of ZnO thin films by plasma assisted and Au-catalyst assisted MOCVD

The structural, morphological and optical properties of ZnO thin films grown by metal organic chemical vapor deposition (MOCVD) also plasma-assisted (PA-MOCVD) and Au-catalyst assisted (Au-MOCVD) are investigated. A new precursor Zn(TTA)(2)TMED (HTTA = 2-thenoyltrifluoroacetone, TMED = N,N,N',N'- tetramethylethylendiamine) and O-2 have been used to grow film on various substrates, including Si(100), alpha-Al2O3(0001) and quartz. Spectroscopic ellipsometry is used for investigating the correlation between film nanostructure and optical properties (exciton of ZnO appears in dielectric function). It has been found that the O-2 plasma assisted growth results in highly (0001) oriented ZnO films on all investigated substrates, with better optical quality as indicated by a sharp and intense exciton in the dielectric function spectra. Conversely, highly textured and rough films are deposited by MOCVD and also using the Au-catalyst. In the latter case, coupling ZnO with Au nanoparticles used as catalyst results in an enhancement of the Au surface plasmon resonance peak at 2.2 eV