Search

The moiré pattern restricts the electronic states of transition metal bilayers, thus extending the concept of the magic angle found in twisted bilayer graphene to semiconductors. Here, we have studied the electronic structure of the twisted bilayer WTe2 using first-principle calculations. Our result shows that a twist significantly changes the band structure, resulting in the bandgap engineering when the twisted bilayer of WTe2 is turning to a specific angle. The electronic structure is changed by the change of the twist angle. Interestingly, a semiconductor-to-metal phase transition is found at a twist angle of 15°. Our results provide a reference for the regulation of two-dimensional band structures. These results are important for understanding the electronic structure of twisted systems and for future applications in electronic devices.

Electronic structures of non-twisted and twisted WTe2/WSe2 heterojunction bilayers were investigated using first-principles calculations. Our results show that, for the twisted WTe2/WSe2 heterojunction bilayer, the bandgaps are all direct bandgaps, and the bandgap (K–K) increases significantly when the twist angle is from 0° to 10°. However, when the twist angle is from 11° to 14.2°, the bandgaps are all indirect bandgaps and the bandgap (G–K) significantly reduces. The band structure of the twisted WTe2/WSe2 heterojunction bilayer differs significantly from that of the non-twisted. Twisted WTe2/WSe2 heterojunction bilayers can be seen as a direct bandgap to an indirect bandgap conversion when turned to a certain angle. Interestingly, the bandgap of the WTe2/WSe2 heterojunction bilayer is very sensitive to the change in the twist angle. For example, when the twist angle is 10.5°, a maximum bandgap will appear. However, the minimum bandgap is 0.041 eV at 14.2°. Our findings have important guidance for device tuning of two-dimensional heterojunction materials.