2D MATERIALS. Observation of tunable band gap and anisotropic Dirac semimetal state in black phosphorus.
Black phosphorus consists of stacked layers of phosphorene, a two-dimensional semiconductor with promising device characteristics. We report the realization of a widely tunable band gap in few-layer black phosphorus doped with potassium using an in situ surface doping technique. Through band structure measurements and calculations, we demonstrate that a vertical electric field from dopants modulates the band gap, owing to the giant Stark effect, and tunes the material from a moderate-gap semiconductor to a band-inverted semimetal. At the critical field of this band inversion, the material becomes a Dirac semimetal with anisotropic dispersion, linear in armchair and quadratic in zigzag directions. The tunable band structure of black phosphorus may allow great flexibility in design and optimization of electronic and optoelectronic devices.
Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
Jimin
J
Kim
Department of Physics, Yonsei University, Seoul 120-749, Korea. Center for Computational Studies of Advanced Electronic Material Properties, Yonsei University, Seoul 120-749, Korea.
Seung Su
SS
Baik
Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea. Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 790-784, Korea.
Sae Hee
SH
Ryu
Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea. Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 790-784, Korea.
Yeongsup
Y
Sohn
Department of Physics, Yonsei University, Seoul 120-749, Korea.
Soohyung
S
Park
Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784, Korea.
Byeong-Gyu
BG
Park
Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Jonathan
J
Denlinger
Department of Physics, Yonsei University, Seoul 120-749, Korea.
Yeonjin
Y
Yi
Department of Physics, Yonsei University, Seoul 120-749, Korea. Center for Computational Studies of Advanced Electronic Material Properties, Yonsei University, Seoul 120-749, Korea.
Hyoung Joon
HJ
Choi
Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea. Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 790-784, Korea. keunsukim@postech.edu.
Keun Su
KS
Kim