On the control of film growth of PE-CVD ZnO:Al for thin film photovoltaics

M. Creatore, I. Volintiru, C.I.M.A. Spee, M.C.M. Sanden, van de

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Abstract

ZnO:Al is a transparent conductive oxide studied as a valid alternative to tin-doped indium oxide and SnO2:F for flat panel displays and solar cells. In this work, a remote plasma-enhanced CVD process based on diethylzinc/trimethylaluminum/oxygen mixts. is used to deposit ZnO:Al layers, which have already demonstrated to be suitable as front electrodes in thin film a-Si solar cells. The layers exhibit a strong sheet resistance gradient with increasing film thickness, i.e. from 180 W/square at 300 nm to 5.5 W/square at 1300 nm. This gradient represents a major disadvantage when ZnO is used as top contact and deposited after the solar cell structure has been grown. In this work the focus is on the overall effect of the working pressure, which is found to be a key parameter in controlling the sheet resistance and film morphol. of the ZnO:Al layers. By decreasing the pressure from 1.5 to 0.4 mbar, a transition from high surface roughness, large grain size pyramid-like to smooth and small grain pillar-like growth mode is obsd. On the basis of these observations, supported by an extensive film characterization (e.g. Hall, in situ real time spectroscopic ellipsometry, TOF-SIMS), a tentative growth model for the ZnO:Al layers is formulated. [on SciFinder (R)]
Original languageEnglish
Title of host publicationAnnual Technical Conference Proceedings
Pages86-89
Publication statusPublished - 2008

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Creatore, M., Volintiru, I., Spee, C. I. M. A., & Sanden, van de, M. C. M. (2008). On the control of film growth of PE-CVD ZnO:Al for thin film photovoltaics. In Annual Technical Conference Proceedings (pp. 86-89)