Electric-field-induced self-assembled one-dimensional nanostructures in CdX and HgX (X=Se, Te) thin films

Self-assembling due to the presence of electric field during deposition in the spray deposited nanocrystalline CdX and HgX (X=Se and Te) thin films is reported. The films are deposited using solvothermally synthesized nanoparticles dispersed in 1-butanol and sprayed on the glass substrates at 200 °C without any voltage as well as by applying a voltage to the nozzle. The electron microscopy studies reveal the formation of nanorods for the films deposited with the voltage. The X-ray diffractograms of CdSe films deposited without voltage and with voltage show hexagonal crystal structure. On the other hand, CdTe films deposited without voltage show cubic crystal structure and the films deposited with voltage show hexagonal crystal structure. HgX films deposited without and with voltage show cubic crystal structure and there is no nanorod formation below 700 V. HRTEM studies show the growth direction of the CdX nanostructures. In view of the self-assembly observed under voltage, the induced dipole moment and the resultant electrostatic interaction are expected to be the driving force for the growth of nanorods. Blueshift in the band gap is observed for all the films deposited without and with voltages, and it is attributed to the quantum confinement effect due to the formation self-assembled one-dimensional nanostructures.