Band diagram of the AlF3 /SiO2/Si system

The material system aluminum fluoride-silicon oxide-silicon (AlF3/SiO2/Si) can localize a high density of fixed negative charges in fluorine (F) vacancies within AlF3, serving as a source for a strong drift field. This assignment is corroborated by a determination of the stoichiometry with Rutherford backscattering techniques and the transient response of the negatively charged defects with deep level transient spectroscopy. From the density-functional calculations of stoichiometric and understoichiometric AlF3, we deduce a microscopic picture where the energetic eigenstates of the the singly and doubly occupied F vacancies surround the Fermi energy. The lineup of the band edges of the system AlF3/SiO2/Si is determined by self-consistent electrostatic calculations including local charges, resulting in excellent agreement with the energetics deduced from the transient response of the charged defects. (C) 2005 American Institute of Physics.