Spray coating assisted solution-processed fabrication of phosphorus doped nanocrystalline silicon thin films: Micro-structure evolution, optical and electrical properties

摘要

In view of development of cost effective solution-processed Si based devices, a facile synthesis method using spray coating technique is proposed in this study. The thin films of phosphorus doped nanocrystalline Si powder were fabricated by spraying of the doped Si powder on the quartz glass substrate. For spraying, the powder was dispersed in acetone and sprayed, by an air spray gun, on the substrate. The sprayed film was then sintered at 700 degrees C for 90 min in argon gas atmosphere. Crystallite size in powder and thin films was found to be in the nanometer range as evaluated by XRD and TEM. Raman spectroscopy confirmed the presence of nano and micro crystallites in the film, and complete absence of amorphous phase. Strain, stresses and dislocation densities were calculated. The surface morphology of thin films was studied by SEM and AFM. The surface roughness and porosity in the thin film was found as 60 nm and 14%, respectively. AFM images show the presence of nanocrystallites and porosity in the prepared films. The charge carrier concentrations and hall mobility were found to be 3 X 10(17) cm(-3) and 13.1 cm(2)/V.s, respectively. The optical performance of the film was evaluated by studying optical absorbance, absorption coefficient, bandgap, and reflectivity. The developed synthesis route also paves a way for recycling and reusing of the unusable Si wafers. The presented research provides a possibility to fabricate low cost solution-processed Si thin film devices using engineered particles as a precursor.