Controlled Doping Engineering in 2D MoS 2 Crystals toward Performance Augmentation of Optoelectronic Devices.

Doping engineering of two-dimensional (2D) semiconductors is vital for expanding their device applications, but has been limited by the inhomogeneous distribution of doping atoms in such an ultrathin thickness. Here, we report the controlled doping of Sn heteroatoms into 2D MoS2 crystals through a single-step deposition method to improve the photodetection ability of MoS2 flakes, whereas the host lattice has been well reserved without the random aggregation of the introduced atoms. Atomic-resolution and spectroscopic characterizations provide direct evidence that Sn atoms have been substitutionally doped at Mo sites in the MoS2 lattice and the Sn dopant leads to an additional strain in the host lattice. The detection performance of Sn-doped MoS2 flakes exhibits an order of magnitude improvement (up to Rλ ≈ 29 A/W, EQE ≈ 7.8 × 103%, D* ≈ 1011 Jones@470 nm) as compared with that of pure MoS2 flakes, which is associated with electrons released from Sn atoms. Such a substitutional doping process in TMDs provides a potential platform to tune the on-demand properties of these 2D materials.