Characterization of Si quantum dots synthesized at various operating pressures for photovoltaic application

We have synthesize and characterize Si quantum dots prepared at 10, 15 and 20 Torr working pressure of Ar having fixed substrate temperatures 133 Kusing physical vapour condensation technique. The Si quantum dots were investigated by FESEM, TEM, XRD, UV-visible and PL spectroscopy. The studies on x-ray diffraction indicate the amorphous texture of Si quantum dots. TEM studies show that the synthesized quantum dots have an average size in between 5 to 9 nm. The optical absorbance studies on thin films of Si quantum dots shows direct band gap. The PL spectra indicate a sharp peak at 432 nm, which confirms the developments of Si quantum dots. The dc conductivity (sigma(dc)) was measured on thin films of Si quantum dots from 303 K to 454 K and found to increase exponentially with increasing temperature. This designates that the conduction in Si quantum dots is owed to activation procedure and representing the semiconductor nature.