p-Type hydrogenated silicon oxide thin film deposited near amorphous to microcrystalline phase transition and its application to solar cells

We have developed p type hydrogenated silicon oxide (p type SiO:H) films which fabricated near the phase between amorphous and microcrystalline silicon oxide (a-SiO:H and μc-SiO:H) transition region in order to improve the open circuit voltage ( V oc ) and short circuit current density ( J sc ), of...

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Bibliographic Details
Published in:	Current applied physics Vol. 11; no. 1; pp. S47 - S49
Main Authors:	Sriprapha, Kobsak, Sitthiphol, Nopphadol, Sangkhawong, Puchong, Sangsuwan, Vichit, Limmanee, Amornrat, Sritharathikhun, Jaran
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 2011
Subjects:	carbon dioxide oxygen p-Type hydrogenated amorphous silicon oxide Phase transition photovoltaic cells physics Protocrystalline silicon oxide silicon Thin film silicon solar cell vapors zinc oxide p-Type hydrogenated amorphous silicon oxide Protocrystalline silicon oxide Thin film silicon solar cell Phase transition
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Summary:	We have developed p type hydrogenated silicon oxide (p type SiO:H) films which fabricated near the phase between amorphous and microcrystalline silicon oxide (a-SiO:H and μc-SiO:H) transition region in order to improve the open circuit voltage ( V oc ) and short circuit current density ( J sc ), of thin film silicon solar cells. A mixed gas of diborane (B 2H 6) and trimethylboron (B(CH 3) 3 or TMB) was used as a doping gas while carbon dioxide (CO 2) was applied as a source of oxygen atom (O). The p type SiO:H films were deposited by a 60 MHz plasma enhanced chemical vapor deposition (PECVD) technique. We found that, the phase transition of amorphous to microcrystalline region could be controlled by changing CO 2 flow rate. By increasing the CO 2 flow rate from 0 to 1.0 sccm, the peak position of Raman spectra changed from 520 cm −1 to 480 cm −1. The conductivity of the p type SiO:H films decreased from 1.65 × 10 −1 S/cm (μc-SiO:H phase) to 1.12 × 10 −5 S/cm (a-SiO:H phase) when the CO 2 flow reached 1.0 sccm. The E opt of all p type SiO:H films were found in the range of 1.94–2.09 eV. By applying the p type SiO:H films to p-i-n solar cells with the structure of TCO/p/i-a-Si:H (400 nm)/n/ZnO/Ag, it was found that solar cells with p-layer deposited just below the onset of the μc-SiO:H indicated better performance than solar cells using p-a-SiO:H or p-μc-SiO:H layer. They indicated relatively high V oc and J sc , resulted in the highest cell conversion efficiency of 8.5%. ► p type SiO:H films which fabricated near the a-SiO:H to μc-SiO:H transition region. ► A mixed gas of diborane (B 2H 6) and trimethylboron (B(CH 3) was used as a doping gas. ► The phase transition of p-layer could be controlled by changing CO 2 flow rate. ► The best cell performance obtained at p-layer deposited below the onset of μc-SiO:H.
Bibliography:	http://dx.doi.org/10.1016/j.cap.2010.11.008
ISSN:	1567-1739 1878-1675
DOI:	10.1016/j.cap.2010.11.008