THICKNESS AND DEFECT DEPENDENT structural AND OPTICAL PROPERTIES OF CdSe NANOCRYSTALLINE THIN FILM

Dhaneswar Kalita; Sanjib Karmakar

Volume : V, Issue : V, May - 2016

THICKNESS AND DEFECT DEPENDENT structural AND OPTICAL PROPERTIES OF CdSe NANOCRYSTALLINE THIN FILM

Dhaneswar Kalita, Sanjib Karmakar

Abstract :

Nano crystalline CdSe thin films were prepared on glass substrates using by the thermal evaporation technique under vacuum (~10–5 torr) at substrate temperature 273 K. The structural and optical properties of CdSe thin films were characterized using by X–ray diffraction and ultraviolet visible spectrum. The optical band edge of the CdSe thin film having different grain distribution was estimated from absorption data of a UV–VIS spectrophotometer in the wavelength range from 300 to 1100 nm. The films have a direct allowed electronic transitions and the optical absorption are shifted to the low energies with the increase of thickness of the films. The optical band gap of CdSe thin films were estimated from experimental data and observed that the band gap energies decreased from 2.34 eV to 2.03 eV as the thickness of the films increased. The extinction coefficient, refractive index and the dielectric constants (real, imaginary) were investigated and found increased with the increases in thickness