ABSTRACTBoron-doped zinc oxide (ZnO) films deposited by Low-Pressure Chemical Vapor Deposition (LPCVD) technique are used as Transparent Conductive Oxide (TCO) to contact thin-film silicon solar cells. In this paper, the effect of boron introduced as dopant during ZnO formation is studied. These films are highly transparent in the visible range, whereas in the near infrared region their transmittance decreases with the increase of boron content due to free carrier absorption (FCA). A shifting of the fondamental band gap is also observed. The resistivity decreases of about one order of magnitude with the increase of the doping ratio ([B2H6]/[DEZ]) from 0 to 2. This resistivity drop is mainly due to an increase of the free carrier concentration. In low doped samples, Hall mobility increases with grain size, whereas it shows no grain size dependence in highly doped layers. This suggest that the scattering by grain-boundary is the main limiting factor for transport in low doped ZnO samples, whereas in highly doped ZnO films transport is controlled by the ionized impurity scattering within the grains.
