Scalable lateral heterojunction by chemical doping of 2D TMD thin films

Abstract

Scalable heterojunctions based on two-dimensional transitional metal dichalcogenides are of great importance for their applications in the next generation of electronic and optoelectronic devices. However, reliable techniques for the fabrication of such heterojunctions are still at its infancy. Here we demonstrate a simple technique for the scalable fabrication of lateral heterojunctions via selective chemical doping of TMD thin films. We demonstrate that the resistance of large area MoS 2 and MoSe 2 thin film, prepared via low pressure chalcogenation of molybdenum film, decreases by up to two orders of magnitude upon doping using benzyl viologen (BV) molecule. X-ray photoelectron spectroscopy (XPS) measurements confirms n-doping of the films by BV molecules. Since thin films of MoS 2 and MoSe 2 are typically more resistive than their exfoliated and co-evaporation based CVD counterparts, the decrease in resistance by BV doping represents a significant step in the utilization of these samples in electronic devices. Using selective BV doping, we simultaneously fabricated many lateral heterojunctions in 1 cm 2 MoS 2 and 1 cm 2 MoSe 2 films. The electrical transport measurements performed across the heterojunctions exhibit current rectification behavior due to a band offset created between the doped and undoped regions of the material. Almost 84% of the fabricated devices showed rectification behavior demonstrating the scalability of this technique.

Plasmon Triggered, Enhanced Light–Matter Interactions in Au–MoS2 Coupled System with Superior Photosensitivity

“…The characteristic Mo 3d 5/2 (peak at ∼231.0 eV) and Mo 3d 3/2 (peak at ∼234.1 eV) electronic states are shifted toward the higher binding energies by 1.7 eV, as compared to that of pure MoS 2 (∼229.3 eV and ∼232.4 eV, respectively) . The increase in binding energy is attributed to the upshift of the Fermi level due to the n-type doping . The binding energy for Au 4f 7/2 and Au 4f 5/2 electrons is observed to be 83.5 and 87.2 eV, respectively (Figure c).…”

“…37 The increase in binding energy is attributed to the upshift of the Fermi level due to the n-type doping. 38 The binding energy for Au 4f 7/2 and Au 4f 5/2 electrons is observed to be 83.5 and 87.2 eV, respectively (Figure 1c). The binding energy of Au 4f states is found to be shifted to a lower value by ∼0.5 eV, as compared to Au 0 states (4f 7/2 ∼ 84.0 eV and 4f 5/2 ∼ 87.7 eV).…”

Photodetectors of 2D Materials from Ultraviolet to Terahertz Waves

“…Therefore, the more electron–hole pairs generated in the interface layer by light, the greater the current. The built‐in field can be achieved in 2D materials by making chemical doping, [ 18 ] heterostructures, [ 19 ] and split gate tuning. [ 20 ]…”

2D Material‐Based Optical Biosensor: Status and Prospect

“…They have unique optical and photoelectric properties. [ 51 , 52 ] Single‐ or multilayer transition metal dichalcogenides are direct bandgap semiconductors. Their bandgap energy and carrier type (n‐type or p‐type) vary with the composition, structure, and size of the compounds.…”