ZnO:Al films were deposited by RF magnetron sputtering in triode configuration applying an external DC electric field to the substrates. Reflection high-energy electron diffraction measurements characterized the different films as consisting of randomly-oriented zinc blende crystallites or randomly and texture-oriented wurtzite crystallites, as well as of the amorphous phase. The non-resonant Raman spectra are strongly influenced by the presence of a built-in electric field at the grain boundaries and they do not depend on the symmetry of the microcrystallites. The Raman spectra taken at resonant excitation are more sensitive to the presence of the amorphous phase in the films.