Vertical-Tunnel Field-Effect Transistor Based on a Silicon-MoS2 Three-Dimensional-Two-Dimensional Heterostructure.

We present a tunneling field-effect transistor based on a vertical heterostructure of highly p-doped silicon and n-type MoS2. The resulting p-n heterojunction shows a staggered band alignment in which the quantum mechanical band-to-band tunneling probability is enhanced. The device functions in both tunneling transistor and conventional transistor modes, depending on whether the p-n junction is forward or reverse biased, and exhibits a minimum subthreshold swing of 15 mV/dec, an average of 77 mV/dec for four decades of the drain current, a high on/off current ratio of approximately 107 at a drain voltage of 1 V, and fully suppressed ambipolar behavior. Furthermore, low-temperature electrical measurements demonstrated that both trap-assisted and band-to-band tunneling contribute to the drain current. The presence of traps was attributed to defects within the interfacial oxide between silicon and MoS2.

Stretchable thin-film transistors with molybdenum disulfide channels and graphene electrodes.

Two-dimensional (2D) materials including graphene and transition metal dichalcogenides (TMDCs) have attracted great interest as new electronic materials, given their superior properties such as optical transparency, mechanical flexibility, and stretchability, especially for application in next-generation displays. In particular, the integration of graphene and TMDCs enables the implementation of 2D materials-based thin-film transistors (TFTs) in stretchable displays, given that TFTs are the fundamental element of various modern devices. In the present study, we demonstrate chemical-vapor-deposited molybdenum disulfide and graphene-based TFTs on a polymer substrate and investigate the electrical characteristics of TFTs under mechanical deformation to determine the stretchability of our devices. Furthermore, the mechanisms leading to TFT performance degradation are investigated, as they relate to the change in the contact resistance that is closely associated with the relative deformation of 2D materials under mechanical stress. Therefore, the synergetic integration of 2D materials with versatile electrical properties provides an important strategy for creating 2D materials-based stretchable TFTs, thus extending the excellent potential of 2D materials as innovative materials for stretchable active-matrix displays.

Hydrodynamic filtration in microfluidic channels as size-selection process for giant unilamellar vesicles.

We have developed hydrodynamic filtration method in microfluidic device for the efficient size-selection of polydisperse lipid vesicles for giant unilamellar vesicles (GUVs), in which vesicles were formed by electroformation method. Combining pinched flow channel design before hydrodynamic filtration, GUVs were flowed and guided to filtration channels, in which small lipid vesicles were further filtered and GUV were remained in main flow channels. For increasing the selectivity of GUV in outlets, length of slit section, or relative flow rate were controlled and drain channels were introduced for avoiding back flow. At higher flow rate in a pinched flow, the fraction of recovered GUVs (>10 microm) were increased, in which most of small vesicles were filtered.