Enhancement of optical and thermoelectric properties in dysprosium doped ZnO thin films as an impact of non-parabolic band structure

Abstract

Non parabolic band structure proposed by the Single Kane Band (SKB) model is able to explain the optical and thermoelectric properties of Dysprosium (Dy) doped Zinc oxide (ZnO) thin films coated by reactive radio frequency (RF) magnetron sputtering. Thermoelectric devices which are optically transparent possess a good promise for the future energy application. The excessive number of carriers formed by chemical substitution of Dy ion in the host ZnO lattice results in the band filling and cause heavier effective mass for the bands. Anomalous drifting of effective mass from 0.25 me to 1.80 me reduces the mobility of free charge carriers in the deformed potential. Multifunctionality of oxide thin films as transparent conducting oxide (TCO) and thermoelectric (TE) material can be consistent through band filling. Band filling leads to the widening of optical band gap and the heavier effective mass for the improved thermoelectric properties. N type thermoelectric thin films of Dy doped ZnO have been developed in order to maximize the optical transparency (>70% in the visible region), electrical conductivity (σ > 500 S/m at 473 K) and thermoelectric power factor (>25 μW/mK2 at 473 K).