Correlation between Structure and Optoelectronic Properties of Undoped Microcrystalline Silicon

• Published in: Japanese Journal of Applied Physics Vol. 37; no. 4R; p. 1730
• Main Authors: Frank Siebke, Frank Siebke, Shigeo Yata, Shigeo Yata, Yoshihiro Hishikawa, Yoshihiro Hishikawa, Makoto Tanaka, Makoto Tanaka
• Format: Journal Article
• Language: English
• Published: 01.04.1998
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.37.1730

Undoped microcrystalline silicon with various crystallinities was deposited by rf-glow discharge. We investigate the correlation between crystallinity and optoelectronic properties. The use of a constant photocurrent method for characterization of undoped microcrystalline silicon is discussed. In the case of high crystallinity this method measures the true absorption coefficient but with decreasing crystallinity, the constant photocurrent method underestimates the absorption coefficient at low photon energies. At these energies, carriers are mainly photo generated in the crystalline phase. Carriers generated in isolated grains give a smaller contribution to the photocurrent than carriers generated in grains forming percolation paths. This results in a strongly decreased absorption coefficient measured by the constant photocurrent method at photon energies of about 1.7 eV and below. Therefore, stable microcrystalline silicon with a high crystallinity can be easily distinguished from an unstable material with poor crystallinity.