Thinning Effect of Few-Layer Black Phosphorus Exposed to Dry Oxidation

Few-layer black phosphorus (BP) holds significant potential for next-generation electronics due to its tunable bandgap and high carrier mobility. The layer modulation of BP is essential in the applications of electronic devices ascribed to its thickness-dependent electronic properties. However, precisely controlling its thickness still presents a challenge for optimizing performance. In this study, we demonstrate that BP can be precisely thinned when exposed to dry oxygen (40% humidity, low oxygen concentration) in a dark environment, which is different from that exposed to humid oxygen (100% humidity, low oxygen concentration) without light illumination. The thinned BP not only demonstrates enhanced stability but also exhibits significant improvements in its electrical properties. The variation in bandgap from 0.3 to 2 eV, resulting in the I_ON/I_OFF ratio increased from 10³ to 10⁶, and the hole mobility improved from 235 cm² V^-1 s^-1 to 851 cm² V^-1 s^-1, was ascribed to the layer-by-layer thinning and p-type doping effects induced by the formed P_xO_y. Our finding demonstrates significant potential of BP in future nanoelectronic and optoelectronic applications.