Al-Doped ZnO/Silicon-rich Oxide Superlattices with High Room-Temperature Thermoelectric Figure of Merit

[Display omitted] •Silicon-rich oxide insertion improves thermoelectric properties of ZnO and AZO.•The superlattices of silicon and AZO increases scattering interfaces for phonons.•Thin silicon-rich oxide in amorphous AZO matrix form silicon nano-crystals. This research reports the thermoelectric properties of the Al-doped ZnO (AZO)/silicon-rich oxide (SRO) superlattices. The thermoelectric figure of merit (ZT) as functions of the grain size, thickness of the superlattices, the number of SRO layers, and conductance were studied. The use of the SRO layers markedly improved the thermoelectric ZT. Moreover, the replacement of ZnO by AZO further increased the ZT. The ZT value of the AZO/SRO superlattices was as high as 0.44 when the total thickness was 45 nm and three SRO interlayers were inserted. The improvement of ZT was contributed by the reduction of the grain size, formation of the Si nanocrystals and the increase in the electrical conductance caused by using SRO interlayers and Al doping.