Electrically driven lasers from van der Waals heterostructures.

Van der Waals heterostructures (vdWHs) have opened new avenues for fundamental scientific studies and design of novel devices. Although numerous reports have demonstrated vdWH optoelectronic devices, no report on vdWH lasers can be found to date. In this paper we demonstrated electrically driven vdWH lasers for the first time, and the lasers were realized from ZnO microwire/MgO/p-GaN structures. By coating Ag films on the top surfaces of the ZnO microwires, the current injection and lasing directionality of the vdWH lasers have been improved significantly, and this improvement can be attributed to the high conductivity and reflectivity of the Ag film. The output power of the device can reach 2.41 μW under 14 mA drive current, which is among the highest values ever reported for ZnO based lasers. Our results may provide a promising way to electrically pumped lasers based on micro/nano-structures.