Organic-Component Dependent Crystal Orientation and Electrical Transport Properties in ALD/MLD Grown ZnO-Organic Superlattices

Two series of ZnO-organic superlattice thin films are fabricated with systematically controlled frequencies of monomolecular hydroquinone (HQ) or terephthalic acid (TPA) based organic layers within the ZnO matrix using the atomic/molecular layer deposition (ALD/MLD) technique. The two different organic components turn the film orientation to different directions and affect the electrical transport properties differently. While the TPA layers enhance the c-axis orientation of the ZnO layers and act as electrical barriers depressing the electrical conductivity even in low concentrations, adding the HQ layers enhances the a-axis orientation and initially increases the carrier concentration, effective mass, and electrical conductivity. The work thus demonstrates the intriguing but little exploited role of the organic component in controlling the properties of the inorganic matrix in advanced layer-engineered inorganic-organic superlattices.