Ultimate Thin Vertical p-n Junction Composed of 2D Layered Molybdenum Disulfide

TL;DR

This paper demonstrates the fabrication of ultrathin vertical p-n junctions in MoS2, revealing ambipolar transport, rectification behaviors, and potential for flexible electronics, with the thinnest junction reaching 3 nm.

Contribution

It introduces a novel method to create ultrathin MoS2 p-n junctions with controlled doping and characterizes their electronic properties at atomic-scale thicknesses.

Findings

Achieved 3 nm thick MoS2 p-n junctions.

Observed ambipolar carrier transport and rectification behaviors.

Doping depth of 1.5 nm enables ultrathin device fabrication.

Abstract

Semiconducting 2D crystals are currently receiving significant attention due to their great potential to be an ultra-thin body for efficient electrostatic modulation which enables to overcome the limitations of silicon technology. Here we report that, as a key building block for 2D semiconductor devices, vertical p-n junctions are fabricated in ultrathin MoS2 by introducing AuCl3 and benzyl viologen dopants. Unlike usual unipolar MoS2, the MoS2 p-n junctions show (i) ambipolar carrier transport, (ii) current rectification via modulation of potential barrier in films thicker than 8 nm, and (iii) reversed current rectification via tunneling in films thinner than 8 nm. The ultimate thinness of the vertical p-n homogeneous junctions in MoS2 is experimentally found to be 3 nm, and the chemical doping depth is found to be 1.5 nm. The ultrathin MoS2 p-n junctions present a significant potential of the 2D crystals for flexible, transparent, high-efficiency electronic and optoelectronic applications.