Alkene-Catalyzed Rapid Layer-by-Layer Thinning of Black Phosphorus for Precise Nanomanufacturing.

Black phosphorus (BP) is a promising material for electronic and optoelectronic applications. However, it is still challenging to obtain geometrically well-defined BP with desirable thickness. The method involving rapid BP surface reaction via alkene-catalyzed oxidation and easy removal of reactants by a mechanical effect was proposed to achieve the precise layer-by-layer thinning and real-time thickness monitoring of BP for nanopatterning with high spatial resolution based on mechanical scanning probe nanolithography. The enhanced electron affinity of oxygen with the assistance of a carbon-carbon double bond (C═C) in the alkene was demonstrated by density functional theory calculations, shortening the BP surface oxidation period by 99%, which provides access for the rapid thinning. The few-layer BP nanoflake with nested structure and arbitrary thickness on various substrates and the nanopatterned heterojunctions (BP/graphene and BP/hexagonal boron nitride) can be precisely fabricated by the adjustment of scanning number under a small load. This thinning technology was efficient and universal, which could be used to fabricate a BP field-effect transistor with a thinned channel to enhance the capability for current modulation, showing great potential applications for designing high-performance nanodevices.