The Effect of Negative Bias Voltage on Porous Silica Films Photoluminescence

Abstract

To obtain porous silica films emitting adjustable blue light at room temperature, the plasma enhanced chemical vapor deposition (PECVD) system at atmosphere pressure was. modulated by direct current negative bias voltage. During the variation of bias voltage from −200 V to −850 V, photoluminescence (PL) spectrum expressed the continuous increase of the peak at 410 nm.This PL peak was resolved with four Gaussian bands, which responded respective possible mechanism. Microstructure of the films exhibited higher porosity at −850 V bias voltage and the size of silica particles decreased Fourier transform infrared spectra (FTIR) showed Si-O-Si groups grew in quantity and Si-H chemical bonds disappeared with the increase of bias voltage. All of these indicated that Si-H bonds under low bias voltage quenched PL, and while Si–O bonds and high porosity under high bias voltage strengthened the intensity of PL.

Keywords:

• Photoluminescence
• PECVD
• porous silica
• negative bias voltage

Acknowledgments

The authors would like to acknowledge the supports of National Nature Science Foundation of China (Grant No 10775031, 10835004 and 11005017) and the Fundamental Research Funds for the Central Universities. (2010A09-4-1)