Influence of heat generated by a Raman excitation laser on the structural analysis of thin amorphous silicon film

• DOI: 10.1016/j.apsusc.2015.12.091
• Publication Date: 2015-12-18T11:21:37Z
• Authors: P. Novák; J. Očenášek; L. Prušáková; V. Vavruňková; J. Savková; J. Rezek
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract In the present work we investigate thin amorphous silicon film fabricated by plasma enhanced chemical vapor deposition. In particular, we analyze changes in the recorded Raman spectra caused by excitation laser irradiation. Solid phase crystallization, hydrogen diffusive outflow and Raman spectra peak shifts have been observed experimentally and analyzed numerically. The role of film thickness on all these features is pointed out. The study involves laser powers between 0.1 mW and 10 mW focused to a spot diameter of ∼1 μm and film thicknesses between 50 and ∼2000 nm. Additionally, the laser induced temperature fields were analyzed by means of numerical simulation and the Raman spectral shift trough Balkanski model. Results are correlated to structural analysis by Raman spectroscopy, optical microscopy, scanning electron microscopy and atomic force microscopy. It was found that the hydrogen content and solid phase fraction identified by Raman spectroscopy are highly sensitive to the applied excitation laser power.