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Real Time Optics of p-Type Microcrystalline Silicon Deposition On Specular and Textured ZnO-Coated Glass

Published online by Cambridge University Press:  17 March 2011

Pablo I. Rovira ,
Andre S. Ferlauto ,
Randy J. Koval ,
Christopher R. Wronski ,
Robert W. Collins  and
Gautam Ganguly
Pablo I. Rovira
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA
Andre S. Ferlauto
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA
Randy J. Koval
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA
Christopher R. Wronski
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA
Robert W. Collins
Affiliation:
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA
Gautam Ganguly
Affiliation:
BP Solarex, Thin Film R&D, Toano, VA
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Abstract

In this study, we optimize the plasma-enhanced chemical vapor deposition (PECVD) process to achieve high-density nucleation of single-phase microcrystalline silicon (µc-Si:H) p-type layers on zinc oxide (ZnO) surfaces at 200 °C for applications in amorphous silicon (a-Si:H) based p-i-n solar cells. The phase evolution of the Si:H p-layers on specular ZnO-coated glass substrates is characterized using real time spectroscopic ellipsometry (RTSE). The resulting evolutionary phase diagram depicts the accumulated film thickness at which the amorphous-to- microcrystalline (→µc) transition occurs versus the H2-dilution ratio, with all other parameters fixed. Guided by this diagram, we find that high-density microcrystallite nucleation and fully- coalesced µc-Si:H p-layers ∼100 Å thick can be obtained on specular ZnO at 200 Å using a B(CH3)3 doping gas flow ratio of D=[B(CH3)3]/[SiH4]=0.02 and an optimized H2-dilution ratio of R=[H2]/SiH4]=200. Lower H2-dilution levels (R<160) generate purely amorphous or mixed (a+µc) phases, and higher dilution levels (R>200) generate longer induction periods, low-density nucleation, and incomplete coalescence of microcrystallites even after ∼100 Å. The time evolution of the microstructure and the resulting dielectric functions as determined by RTSE are similar for optimized µc-Si:H p-layers ∼200 Å thick prepared on specular and textured ZnO surfaces, indicating that the substrate texturing does not necessitate process reoptimization.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 609: Symposium A – Amorphous & Heterogeneous Silicon Thin Films – 2000 , 2000 , A19.6
Copyright
Copyright © Materials Research Society 1999

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References

REFERENCES

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