Structural, mechanical properties and composition analysis of boron phosphide coatings

► BP coatings were deposited on ZnS by PACVD with B2H6 and PH3 as the precursors. ► The hardness and modulus of the BP coatings decreased with the increase of PH3 flux. ► The composition depth profiles of BP coating were measured by XPS. ► The interfaces between BP coating and ZnS substrate were first researched. ► There is no new stable compound across the interface between BP and ZnS.