Thermoelectric characteristics of (Zn,Al)O/hydroquinone superlattices

Thin ZnO layers doped with aluminum and interspersed with regularly repeating single layers of organic molecules are deposited by a combined atomic layer deposition (ALD) and molecular layer deposition (MLD) method at 220 degrees C using diethyl zinc, trimethyl aluminum, water and hydroquinone (HQ) as precursors. Hydroquinone is found to form distinct layers within the (Zn,Al)O framework such that clear inorganic-organic superlattice structures are realized. Aluminum doping efficiently offsets the decrease in carrier concentration caused by the organic layers, and enables enhanced electrical conductivities for the co-doped (Al plus HQ) thin films. Since superlattice structures in general are known to be highly beneficial in blocking the phonon transport in different materials, our ALD/MLD grown (Zn,Al)O:HQ thin films possess a lot of promise for new types of thermoelectrics.