1 research outputs found
Sulfur-Doped Black Phosphorus Field-Effect Transistors with Enhanced Stability
Black phosphorus
(BP) has drawn great attention owing to its tunable band gap depending
on thickness, high mobility, and large <i>I</i><sub>on</sub>/<i>I</i><sub>off</sub> ratio, which makes BP attractive
for using in future two-dimensional electronic and optoelectronic
devices. However, its instability under ambient conditions poses challenge
to the research and limits its practical applications. In this work,
we present a feasible approach to suppress the degradation of BP by
sulfur (S) doping. The fabricated S-doped BP few-layer field-effect
transistors (FETs) show more stable transistor performance under ambient
conditions. After exposing to air for 21 days, the charge-carrier
mobility of a representative S-doped BP FETs device decreases from
607 to 470 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> (remained as high as 77.4%) under ambient conditions and a large <i>I</i><sub>on</sub>/<i>I</i><sub>off</sub> ratio of
∼10<sup>3</sup> is still retained. The atomic force microscopy
analysis, including surface morphology, thickness, and roughness,
also indicates the lower degradation rate of S-doped BP compared to
BP. First-principles calculations show that the dopant S atom energetically
prefers to chemisorb on the BP surface in a dangling form and the
enhanced stability of S-doped BP can be ascribed to the downshift
of the conduction band minimum of BP below the redox potential of
O<sub>2</sub>/O<sub>2</sub><sup>–</sup>. Our work suggests
that S doping is an effective way to enhance the stability of black
phosphorus