Observation of tunable band gap and anisotropic Dirac semimetal state in black phosphorus

Abstract

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.

Electronic structure and thermoelectric transport of black phosphorus

“…Strain-induced band gap modifications [3,23,24] with tunable semiconductor to anisotropic Dirac semimetal [25] or the existence of a superconducting phase transition under pressure [26] might be linked to selective low-energy electronic reconstruction with characteristics akin to correlated electron systems [27]. Consistent with graphite [28] and elemental bismuth [29], sizable many-body interactions qualifies bulk BP as orbital-selective semimetal hosting renormalized Fermi liquid (FL) electronic states at low energies.…”

Spin-resolved photoemission study of epitaxially grown MoSe2and WSe2thin films

“…They often exhibit versatile electronic structure controllable by thickness, surface chemical adsorption, and strain [5,6,7]. They can also be stacked into heterostructures to develop a new state in the interfaces [8] as well as through proximity effect [9].…”

Exploring the Formation of Black Phosphorus Intercalation Compounds with Alkali Metals

“…It has recently been predicted that the electronic properties of BP can be modulated by strain or electric field 17, 18. Moreover, surface doping with K atoms leads to a tunable band gap in single‐crystal BP, leading a metallic state yielding with a significant improvement of its electronic transport 19, 20. In this regard, the intercalation of BP with donor‐type alkali metals could be envisioned as a promising strategy to electronically dope BP under atmospheric pressure.…”