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Amorphous/Microcrystalline Phase Control in Silicon Film Deposition for Improved Solar Cell Performance

  • Joohyun Koh (a1), H. Fujiwara (a2), Yeeheng Lee (a1), C. R. Wronski (a1) and R. W. Collins (a1)...

Abstract

Real time optical studies have provided insights into the growth of hydrogenated amorphous silicon (a-Si:H) and microcrystalline silicon (μc-Si:H) thin films by plasma-enhanced chemical vapor deposition as a function of the H2-dilution gas flow ratio Research-article=[H2]/[SiH4], the accumulated film thickness db, and the substrate material. Results pertinent to the optimization of a-Si:H-based solar cells have been obtained in studies of Si film growth at moderate to high R on dense amorphous semiconductor film surfaces. For depositions with 15≤Research-article≤80 on freshly-deposited a-Si:H, initial film growth occurs in the amorphous phase. Upon continued growth, however, a transition is observed as crystallites begin to nucleate from the amorphous film. The thickness at which this amorphous-to-microcrystalline (a→μc) transition occurs is found to decrease with increasing R.Based on these results, a deposition phase diagram has been proposed that describes the a–gc transition as a continuous function of R and db. We find that the optimum stabilized a-Si:H p-i-n solar cell performance is obtained in an i-layer growth process that is maintained as close as possible to the phase boundary (but on the amorphous side) versus film thickness.

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Amorphous/Microcrystalline Phase Control in Silicon Film Deposition for Improved Solar Cell Performance

  • Joohyun Koh (a1), H. Fujiwara (a2), Yeeheng Lee (a1), C. R. Wronski (a1) and R. W. Collins (a1)...

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