Molybdenum oxide MoO_x: A versatile hole contact for silicon solar cells

This letter examines the application of transparent MoO_x (x < 3) films deposited by thermal evaporation directly onto crystalline silicon (c-Si) to create hole-conducting contacts for silicon solar cells. The carrier-selectivity of MoO_x based contacts on both n- and p-type surfaces is evaluated via simultaneous consideration of the contact recombination parameter J_0c and the contact resistivity ρ_c. Contacts made to p-type wafers and p⁺ diffused regions achieve optimum ρ_c values of 1 and 0.2 mΩ·cm², respectively, and both result in a J_0c of ∼200 fA/cm². These values suggest that significant gains can be made over conventional hole contacts to p-type material. Similar MoO_x contacts made to n-type silicon result in higher J_0c and ρ_c with optimum values of ∼300 fA/cm² and 30 mΩ·cm² but still offer significant advantages over conventional approaches in terms of contact passivation, optical properties, and device fabrication.