We report the realization of field-effect transistors (FETs) made with chemically synthesized multilayer 2D crystal semiconductor MoS 2 . Electrical properties such as the FET mobility, subthreshold swing, on/off ratio, and contact resistance of chemically synthesized (s-) MoS 2 are indistinguishable from that of mechanically exfoliated (x-) MoS 2 , however flat-band voltages are different, possibly due to polar chemical residues originating in the transfer process.Electron diffraction studies and Raman spectroscopy show the structural similarity of s-MoS 2 to x-MoS 2 . This initial report on the behavior and properties of s-MoS 2 illustrates the feasibility of electronic devices using synthetic layered 2D crystal semiconductors.

We investigated the dependence of grain size on the performance of a polycrystalline silicon (poly-Si) channel TFT for application to 3D NAND Flash memory devices. It has been found that the device performance and memory characteristics are strongly affected by the grain size of the poly-Si channel. Higher on-state current, faster program speed, and poor endurance/reliability properties are observed when the poly-Si grain size is large. These are mainly attributed to the different local electric field induced by an oxide valley at the interface between the poly-Si channel and the gate oxide. In addition, the trap density at the gate oxide interface was successfully measured using a charge pumping method by the separation between the gate oxide interface traps and traps at the grain boundaries in the poly-Si channel. The poly-Si channel with larger grain size has lower interface trap density.