Topological surface currents accessed through reversible hydrogenation of the three-dimensional bulk

Hydrogen can be incorporated within a solid and drastically modify its electronic and structural state. Here, the authors report reversible binding of H+ ions to chalcogens in the Bi2Te3 class of topological insulators and magnets, allowing Fermi level tuning into the bulk gap without altering carrier mobility or the bandstructure. Hydrogen, the smallest and most abundant element in nature, can be efficiently incorporated within a solid and drastically modify its electronic and structural state. In most semiconductors interstitial hydrogen binds to defects and is known to be amphoteric, namely it can act either as a donor (H+) or an acceptor (H-) of charge, nearly always counteracting the prevailing conductivity type. Here we demonstrate that hydrogenation resolves an outstanding challenge in chalcogenide classes of three-dimensional (3D) topological insulators and magnets - the control of intrinsic bulk conduction that denies access to quantum surface transport, imposing severe thickness limits on the bulk. With electrons donated by a reversible binding of H+ ions to Te(Se) chalcogens, carrier densities are reduced by over 10(20)cm(-3), allowing tuning the Fermi level into the bulk bandgap to enter surface/edge current channels without altering carrier mobility or the bandstructure. The hydrogen-tuned topological nanostructures are stable at room temperature and tunable disregarding bulk size, opening a breadth of device platforms for harnessing emergent topological states.

Automated summary

This study reports reversible binding of H+ ions to chalcogens in topological insulators and magnets, allowing for the tuning of the Fermi level without altering carrier mobility or the bandstructure. The hydrogen-tuned topological nanostructures are stable at room temperature, opening up a range of possibilities for harnessing emergent topological states.