Spectroscopic identification of ultranano-crystalline phases within amorphous/nano-crystalline silicon

Mansi Sharma1,2, Deepika Chaudhary1,2, S. Sudhakar1, Preetam Singh1, K. M. K. Srivatsa1,2, Sushil Kumar1,2*

1Network of Institutes for Solar Energy (CSIR-NISE), Physics of Energy Harvesting Division, CSIR – National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012, India

2Academy of Scientific and Innovative Research (AcSIR), CSIR-NPL Campus, Dr. K.S. Krishnan Marg, New Delhi 110012, India 

Adv. Mater. Lett., 2017, 8 (2), pp 163-169

DOI: 10.5185/amlett.2017.6451

Publication Date (Web): Dec 27, 2016

E-mail: skumar@ nplindia.org

Abstract


The structural transition in accordance to nano sized grain distribution within the amorphous silicon matrix has been described on the basis of spectroscopic analysis as a result of variable input power applied during growth via plasma enhanced chemical vapor deposition (PECVD) process. For this, characterization techniques like micro-ellipsometer, Raman, Field emission Scanning electron microscope (FESEM), and Fourier transform infrared spectroscopy (FTIR) have been effectively utilized to identify transitions in these films particularly in terms of crystallite size (within 1-4 nm) and optical constants. These results indicate that at and above 30 W applied power the separation of two zones takes place as ultranano to nano, leading to the formation of denser matrix having uniformly distributed nano-crystallites. Moreover, these results indicate the presence of unrevealed fine crystallites (ultranano-crystalline phase) as a dominating part of grain boundaries, which may be as ultranano-crystallite phase.  The blending of fine nano-crystallites within the amorphous phase might be the possible reason for the formation of nano-crystallites from ultranano-crystallites.

Keywords

PECVD, a/unc/nc-Si:H, spectroscopy ellipsometer.

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