Ultra-low Doping on Two-Dimensional Transition Metal Dichalcogenides using DNA Nanostructure Doped by a Combination of Lanthanide and Metal Ions.

Here, we propose a novel DNA-based doping method on MoS2 and WSe2 films, which enables ultra-low n- and p-doping control and allows for proper adjustments in device performance. This is achieved by selecting and/or combining different types of divalent metal and trivalent lanthanide (Ln) ions on DNA nanostructures, using the newly proposed concept of Co-DNA (DNA functionalized by both divalent metal and trivalent Ln ions). The available n-doping range on the MoS2 by Ln-DNA is between 6 × 10(9) and 2.6 × 10(10 ) cm(-2). The p-doping change on WSe2 by Ln-DNA is adjusted between -1.0 × 10(10) and -2.4 × 10(10 ) cm(-2). In Eu(3+) or Gd(3+)-Co-DNA doping, a light p-doping is observed on MoS2 and WSe2 (~10(10 ) cm(-2)). However, in the devices doped by Tb(3+) or Er(3+)-Co-DNA, a light n-doping (~10(10 ) cm(-2)) occurs. A significant increase in on-current is also observed on the MoS2 and WSe2 devices, which are, respectively, doped by Tb(3+)- and Gd(3+)-Co-DNA, due to the reduction of effective barrier heights by the doping. In terms of optoelectronic device performance, the Tb(3+) or Er(3+)-Co-DNA (n-doping) and the Eu(3+) or Gd(3+)-Co-DNA (p-doping) improve the MoS2 and WSe2 photodetectors, respectively. We also show an excellent absorbing property by Tb(3+) ions on the TMD photodetectors.