Modulation of optoelectric properties of monolayer transition metal dichalcogenides placed on a metal pattern

Atomically thin monolayer transition-metal dochalcogenides (1L-TMDs) are optically active direct band gap semiconducting materials with interesting properties; they are appropriate platform to study and investigate the modulated optoelectronic properties due to locally induced charge transfer phenomenon using various approaches. Herein, 1L-TMDs (MoS2, WS2 and WSe2) grown using chemical vapor deposition (CVD) were transferred above 10-nm-thick patterned platinum (Pt) stripes deposited on SiO2/Si substrate to fabricate a local vertical heterostructure of 1L-TMDs with Pt. The optical characterization showed that the PL intensities of n (p)-type 1L-TMDs, namely MoS2 and WS2 (WSe2), deposited above Pt were reduced with peak positions blue (red)-shifted by 40 (16) meV compared to the samples on SiO2/Si substrates. This was attributed to the transfer of electrons from the 1L-TMDs to the Pt due to a charge transfer process at the interface. At the same time, an enhanced photocurrent, in comparison to 1L-MoS2 alone was observed under a negative gate voltage of - 40 V from the homojunctions of 1L-MoS2 and 1L-MoS2/Pt formed within the same grain structure due to a Pt-induced local p-doping effect. The charge modulation of the opto-electrical properties of 1L-TMDs due to charge transfer caused using patterned metal provides a simple lateral homojunction for enhanced photovoltaic applications.

Automated summary

The study demonstrated that atomically thin monolayer transition-metal dichalcogenides (1L-TMDs) transferred onto patterned platinum (Pt) stripes exhibited reduced photoluminescence intensities and shifted peak positions due to charge transfer to Pt. Additionally, a local p-doping effect induced by Pt was observed, leading to enhanced photocurrent. This suggests that charge modulation through patterned metal can provide a simple lateral homojunction for improved photovoltaic applications.