Phys.org August 18, 2023
Metal contacts to MoS2 field-effect transistors play a determinant role in the device electrical characteristics and need to be chosen carefully. However, they suffer from high contact resistance because of the Schottky barrier and the Fermi level pinning effects that occur at the contact/MoS2 interface. To overcome this issue an international team of researchers (the Netherlands, India) investigated 2D metallic TiSx (x ∼ 1.8) as top contacts for MoS2 FETs using atomic layer deposition for the synthesis of both the MoS2 channels as well as the TiSx contacts and assessed the electrical performance of the fabricated devices. They compared various thickness TiSx grown on MoS2, and electrically compared the resultant devices to the ones with the conventional Ti metal contacts. They found that the replacement of 5 nm Ti bulk contacts with only ∼1.2 nm of 2D TiSx improved the overall device metrics. With such ultrathin TiSx contacts, the ON-state current tripled and increased to ∼35 μA μm−1 and Rc was reduced by a factor of four. According to the researchers these device metric improvements could be mainly associated with an increased level of electrostatic doping in MoS2, because of using 2D TiSx for contacting the 2D MoS2… read more. Open Access TECHNICAL ARTICLE
(a) Schematics of the fabricated MoS2 FETs… Credit: Nanoscale Advances (2023)