Electrically Tunable Energy Bandgap in Dual-Gated Ultra-Thin Black Phosphorus Field Effect Transistors**Supported by the National Basic Research Program of China under Grant Nos 2013CB921900 and 2014CB920900, the National Natural Science Foundation of China under Grant No 11374021) (S. Yan, Z. Xie, J.-H. Chen). K.W. and T.T. acknowledge the support from the Elemental Strategy Initiative conducted by the MEXT, Japan and

Abstract

The energy bandgap is an intrinsic character of semiconductors, which largely determines their properties. The ability to continuously and reversibly tune the bandgap of a single device during real time operation is of great importance not only to device physics but also to technological applications. Here we demonstrate a widely tunable bandgap of few-layer black phosphorus (BP) by the application of vertical electric field in dual-gated BP field-effect transistors. A total bandgap reduction of 124 meV is observed when the electrical displacement field is increased from 0.10 V/nm to 0.83 V/nm. Our results suggest appealing potential for few-layer BP as a tunable bandgap material in infrared optoelectronics, thermoelectric power generation and thermal imaging.