Vanadium doping induces surface morphological changes of CuInS2 thin films deposited by chemical spray pyrolysis

- CIS nanoparticle and V doped CIS nanorod morphological structure thin films are grown by chemical spray pyrolysis.
- Absorption edge of the CIS can be tuned between 814 nm-887 nm with respect to V doping.
- The decrease of energy band gap values are observed with V doping into the host CIS films.
- V dopant is switching from hole dominated p-type to electron dominated n-type behaviour.

Pristine and vanadium (V) doped CuInS2 (CIS) thin films were grown on glass substrate using home-built chemical spray pyrolysis unit. The structural, morphological, optical and electrical properties of pristine and V doped CIS thin films have been systematically inspected. The scanning electron and atomic force microscopic (SEM and AFM) images show the well-interconnected CIS nanoparticles changed to nanorods like morphology with respect to V doping level and also the number density of the nanorods increases with doping level. Furthermore, the formation of CIS nanoparticles and V doped CIS nanorods are authentically confirmed by the transmission electron microscopic (TEM) images. Both pristine and V doped CIS thin films exhibit the body centered tetragonal crystal structure along with polycrystalline nature which is characterized using X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns. The presence of dopant and host elements is confirmed by X-ray photoelectron and energy dispersive X-ray spectroscopic (XPS and EDX) analyses. The decreases of orbital energy gap values are observed using UV-Vis absorption spectra according to V doping level into the CIS lattice sites. A continuous suppression of defect related Cu-Au orderings are observed via Raman spectra as a function of V doping which also indicate the V doping significantly involved during deposition and improve the structural quality of the chalcopyrite CIS film. The electrical properties of CIS films transform enormously, switching from hole dominated (0.3782 S cm−1) p-type to electron dominated (27.16 S cm−1) n-type from 4 wt.% of V doping. It anticipates that this kind of self-assembled 1D CIS nanostructure will give huge interest to tune their physicochemical properties.