Strain Gated Bilayer Molybdenum Disulfide Field Effect Transistor with Edge Contacts.

ABSTRACT: Silicon nitride stress capping layer is an industry proven technique for increasing electron mobility and drive currents in n-channel silicon MOSFETs. Herein, the strain induced by silicon nitride is firstly characterized through the changes in photoluminescence and Raman spectra of a bare bilayer MoS₂ (Molybdenum disulfide). To make an analogy of the strain-gated silicon MOSFET, strain is exerted to a bilayer MoS₂ field effect transistor (FET) through deposition of a silicon nitride stress liner that warps both the gate and the source-drain area. Helium plasma etched MoS₂ layers for edge contacts. Current on/off ratio and other performance metrics are measured and compared as the FETs evolve from back-gated, to top-gated and finally, to strain-gated configurations. While the indirect band gap of bilayer MoS₂ at 0% strain is 1.25?eV, the band gap decreases as the tensile strain increases on an average of ~100?meV per 1% tensile strain, and the decrease in band gap is mainly due to lowering the conduction band at K point. Comparing top- and strain-gated structures, we find a 58% increase in electron mobility and 46% increase in on-current magnitude, signalling a benign effect of tensile strain on the carrier transport properties of MoS₂.

SUBMITTER: Chai Y 

PROVIDER: S-EPMC5301248 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature