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Evolution of Microstructure and Phase in Amorphous, Protocrystalline, and Microcrystalline Silicon Studied by Real Time Spectroscopic Ellipsometry
Solar Energy Materials and Solar Cells (2003)
  • R. W. Collins, The Pennsylvania State University
  • A. S. Ferlauto, The Pennsylvania State University
  • G. M. Ferreira, The Pennsylvania State University
  • Chi Chen, The Pennsylvania State University
  • Joohyun Koh, The Pennsylvania State University
  • R. J. Koval, The Pennsylvania State University
  • The Pennsylvania State University, The Pennsylvania State University
  • Joshua M. Pearce, The Pennsylvania State University
  • C. R. Wronski, The Pennsylvania State University
Abstract
Real time spectroscopic ellipsometry has been applied to develop deposition phase diagrams that can guide the fabrication of hydrogenated silicon (Si:H) thin films at low temperatures (<300°C) for highest performance electronic devices such as solar cells. The simplest phase diagrams incorporate a single transition from the amorphous growth regime to the mixed-phase (amorphous+microcrystalline) growth regime versus accumulated film thickness [the a ͢(a+µc) transition]. These phase diagrams have shown that optimization of amorphous silicon (a-Si:H) intrinsic layers by RF plasma-enhanced chemical vapor deposition (PECVD) at low rates is achieved using the maximum possible flow ratio of H₂ to SiH₄ that can be sustained while avoiding the a͢(a+µc) transition. More recent studies have suggested that a similar strategy is appropriate for optimization of p-type Si:H thin films. The simple phase diagrams can be extended to include in addition the thickness at which a roughening transition is detected in the amorphous film growth regime. It is proposed that optimization of a-Si:H in higher rate RF PECVD processes further requires the maximum possible thickness onset for this roughening transition.
Keywords
  • Spectroscopic ellipsometry; Hydrogenated silicon; Thin films
Publication Date
January 30, 2003
Publisher Statement
2002 Elsevier Science B.V. Preprint uploaded here in compliance with publisher policies. Publisher's version of record: http://dx.doi.org/10.1016/S0927-0248(02)00436-1
Citation Information
R. W. Collins, A. S. Ferlauto, G. M. Ferreira, Chi Chen, et al.. "Evolution of Microstructure and Phase in Amorphous, Protocrystalline, and Microcrystalline Silicon Studied by Real Time Spectroscopic Ellipsometry" Solar Energy Materials and Solar Cells Vol. 78 (2003)
Available at: http://works.bepress.com/jmpearce/72/