Thin hafnia layer on silicon – Study of interfacial charging and charge transfer by resistometry and photoelectrochemistry

Abstract

Oxide layers on silicon (Si) can effectively reduce the surface recombination velocity due to chemical and field-effect passivation, thereby increasing efficiency of PV devices. We propose simple experimental technique that provides information on interfacial Si/oxide charge. Here, interfacial charging in atmosphere of crystalline p-Si with thin hafnia layers deposited using atomic layer deposition and sol–gel techniques were studied by means of the transverse electric resistometry. The samples exhibited the current–voltage (I–V) characteristics, which were analogous to those known for a p-n junction when the Si surface is negatively charged. We also demonstrate the detection of charging effects in electrolyte by measuring the photo-induced capacitance, potential, resistance, and current. The charge transfer inhibition during hydrogen evolution reaction is shown to depend on interfacial charging effects rather than resistance of HfO₂ layer. The proposed methodologies can be extended to a wider range of passivating oxides on semiconductors.