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

摘要

ZnSe films of different thicknesses have been deposited on glass substrates at 150℃ substrate temperature. The films exhibited cubic structure with preferential orientation in the (111) direction. The crystallinity improved and the grain size increased with increase of thickness. A very high value of absorption coefficient (10~4 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 518nm.