Nonconventional Strain Engineering for Uniform Biaxial Tensile Strain in MoS Thin Film Transistors.

Strain engineering has been employed as a crucial technique to enhance the electrical properties of semiconductors, especially in Si transistor technologies. Recent theoretical investigations have suggested that strain engineering can also markedly enhance the carrier mobility of two-dimensional (2D) transition-metal dichalcogenides (TMDs). The conventional methods used in strain engineering for Si and other bulk semiconductors are difficult to adapt to ultrathin 2D TMDs. Here, we report a strain engineering approach to apply the biaxial tensile strain to MoS. Metal-organic chemical vapour deposition (MOCVD)-grown large-area MoS films were transferred onto SiO/Si substrate, followed by the selective removal of the underneath Si. The release of compressive residual stress in the oxide layer induces strain in MoS on top of the SiO layer. The amount of strain can be precisely controlled by the thickness of oxide stressors. After the transistors were fabricated with strained MoS films, the array of strained transistors was transferred onto plastic substrates. This process ensured that the MoS channels maintained a consistent tensile strain value across a large area.