Crystal growth of polycrystalline silicon thin films for solar cells evaluated by scanning probe microscopy

• Published in: Journal of non-crystalline solids 2004-06, Vol.338, p.682-685
• Main Authors: Muhida, R., Kawamura, T., Harano, T., Okajima, M., Toyama, T., Okamoto, H., Honda, S., Takakura, H., Hamakawa, Y.
• Format: Article
• Language: English
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2004.03.065

We have studied the crystalline growth of photovoltaic-device-grade undoped polycrystalline Si (poly-Si) thin films produced by very high frequency (VHF) plasma enhanced chemical vapor deposition (PECVD) using a conductive scanning probe microscope (SPM) technique. Surface morphology and local current images are simultaneously measured for the poly-Si layers with a thickness, d, in the range of 0.5–5 μm. The week correlation between the topological height and the current maximum is observed for the samples with d⩾2 μm. On the other hand, the average current increases by two orders of the magnitude with increasing d from 0.5 to 3 μm. The increase in the crystalline fraction in the initial growth region just adjacent to the substrate after the deposition of the 0.5-μm-thick layer is a possible mechanism for the significant current increase.