Investigation of MoOx/n‐Si strong inversion layer interfaces via dopant‐free heterocontact

Abstract

Transition metal oxides (TMOs)/silicon (Si) heterocontact solar cells are currently under intensive investigation due to their simple fabrication process and less parasitic light absorption compared to traditional heterocontact counterparts. Effective segregation of carriers which is related to carrier‐selective heterocontact is crucial for the performance of photovoltaic devices. Molybdenum oxide (MoOx, x ≤ 3), with a wide bandgap of ∼3.24 eV as well as defect bands derived from oxygen vacancies located inside the band gap, has been introduced to integrate with n‐type Si (n‐Si) as hole selective contact. Here, we utilize a stepwise in situ deposition of MoOx to investigate its interaction with Si by X‐ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) measurements. A strong inversion layer originating from a charge transfer process is demonstrated in the n‐Si surface region upon MoOx contact characterized by XPS, UPS, capacitance–voltage (C–V), and minority charge carrier lifetime mapping measurements.A dopant‐free heterocontact is built within n‐Si with a high built‐in potential (Vbi) of ∼0.80 V which benefits for acquiring a high open circuit voltage (Voc). These results give a detailed interpretation on the carrier transport mechanism of MoOx/n‐Si heterocontact and also pave a new route toward fabricating high efficiency, low‐cost solar cells.