Infrared spectra, optical constants and semiconductor behavior of 5-(2-phenylhydrazono)-3,3-dimethylcyclohexanone thin films

The 5-(2-phenylhydrazono)-3,3-dimethylcyclohexanone (PHDMC) is synthesized by reacting 5,5-dimethylcyclohexane-1,3-dione with 2-phenylhydrazine. Synthesized PHDMC is polycrystalline with monoclinic space group, P21/a. Miller’s indices values for each diffraction peak in the X-ray diffraction spectrum are calculated. Thin films of PHDMC with different thickness values (0.83–1.247 μm) are prepared by thermal evaporation technique and they exhibit amorphous structure. Different vibrational modes, observed in infrared spectra of the powder and thin films, were assigned to the molecular bonding structure of PHDMC compound. The optical properties of PHDMC thin films are investigated by measuring the optical transmittance and reflectance at the normal incidence of the light in the spectral range 200–2500 nm. The refractive and absorption indices of the films are found to be independent of the film thickness range mentioned above. The refractive index is analyzed and the dispersion parameters are extracted. Analysis of the absorption coefficient spectra showed that the films have two major indirect allowed electronic transitions; the corresponding optical band gaps are estimated as 2.1 and 3.2 eV in the framework of electronic band-to-band transition theory. The direct current electrical conductivity measurements showed the semiconductor property of the films.