Low-temperature surface passivation of moderately doped crystalline silicon by atomic-layer-deposited hafnium oxide films

Abstract

Hafnium oxide (HfO2) films synthesized by thermal atomic layer deposition (ALD) are investigated for low-temperature surface passivation of moderately doped crystalline silicon (c-Si). At intermediate bulk injection levels, effective surface recombination velocities of 55 cm/s and 24 cm/s are achieved on 2.1 σcm p-type and 3.3 σcm n-type c-Si, respectively, demonstrating a good level of surface passivation. Contactless corona-voltage measurements show that the good passivation quality is due to both chemical passivation with low interface defect density (∼1011 eV.1 cm -2) and field-effect passivation by negative charges (∼1012 cm-2) in the HfO2 film, which is particularly beneficial for the passivation of p-type c-Si. Fourier transform infrared spectroscopy and crosssectional transmission electron microscopy experiments are conducted to provide insight into the surface passivation mechanism of HfO2 on c-Si. © 2012 The Electrochemical Society.