Modulation of thermoelectric properties of thermally evaporated copper nitride thin films by optimizing the growth parameters

In this paper, we have successfully controlled the thermoelectric properties of copper nitride (Cu3N) thin films by optimizing the post growth nitrogen gas flow time. During thermal evaporation growth of Cu3N thin films, pure copper power (0.12 g) was evaporated on soda lime glass substrate. The boat temperature and nitrogen gas flow rate were fixed at 1010 °C and 100 sccm respectively in horizontal glass tube furnace. In order to study the annealing time duration, all samples were annealed at 320 °C in tube furnace for 2–8 h with constant flow rate of 100 sccm. The formation of Cu3N phase was confirmed by X-Ray Diffraction (XRD) and it was found that crystallinity of grown thin films was improved with annealing time duration. The Seebeck data demonstrated that the value of Seebeck coefficient was increased form 87.59 μV/°C to 134.79 μV/°C as the annealing time duration was increased from 2 to 8 h. This improvement in Seebeck coefficient was associated with the enhancement of samples crystallinity which ultimately increase the mobility of charge carriers. The value of electrical conductivity was also increased from 26.04 S/cm to 33.49 S/cm, therefore we were able to achieve the highest value of power factor (6.08 × 10−5 Wm−1C−2) for sample annealed for maximum time duration. Raman spectroscopy and SEM measurements were additionally performed to strengthen our proposed argument.