On the c-Si surface passivation mechanism by the negative-charge-dielectric Al2 O3

Abstract

Al2 O3 is a versatile high- κ dielectric that has excellent surface passivation properties on crystalline Si (c-Si), which are of vital importance for devices such as light emitting diodes and high-efficiency solar cells. We demonstrate both experimentally and by simulations that the surface passivation can be related to a satisfactory low interface defect density in combination with a strong field-effect passivation induced by a negative fixed charge density Qf of up to 1013 cm-2 present in the Al2 O3 film at the interface with the underlying Si substrate. The negative polarity of Qf in Al2 O3 is especially beneficial for the passivation of p -type c-Si as the bulk minority carriers are shielded from the c-Si surface. As the level of field-effect passivation is shown to scale with Qf2, the high Qf in Al2 O3 tolerates a higher interface defect density on c-Si compared to alternative surface passivation schemes. © 2008 American Institute of Physics.