Influence of thickness on the microstructural, optoelectronic and morphological properties of nanocrystalline ZnSe thin films

ZnSe films of different thicknesses have been deposited on glass substrates at 150 °C substrate temperature. The films exhibited cubic structure with preferential orientation in the (1 1 1) direction. The crystallinity improved and the grain size increased with increase of thickness. A very high value of absorption coefficient (104 cm−1) is observed. Band gap values are found to decrease from about 2.92 to 2.69 eV with increase of the film thickness. The average refractive index value is in the range of 2.39-2.45 for the films with different thickness. It is observed that the conductivity increases continuously with temperature. Laser Raman studies show the presence of peaks at 140.8, 247.2 and 205.3 cm−1 corresponding to 2TA, LO phonon and TO phonon respectively. TEM study confirms the formation of well crystallized ZnSe nanoparticles. Room temperature photoluminescence emission peaks were observed at 426.9, 485 and 518 nm.