Passivated Interfacial Traps of Monolayer MoS2 with Bipolar Electrical Pulse.

Heterogeneous integration of monolayers is an emergent route of spatially combining materials with available platforms for unprecedented properties. A long-standing challenge along this route is to manipulate interfacial configurations of each unit in stacking architecture. A monolayer of transition metal dichalcogenides (TMDs) offers an embodiment of studying interface engineering of integrated systems because optoelectronic performances generally trade off with each other due to interfacial trap states. While ultrahigh photoresponsivity of TMDs phototransistors has been realized, a long response time commonly appears and hinders applications. Here, fundamental processes in excitation and relaxation of the photoresponse are studied and correlated with interfacial traps of the monolayer MoS2. A mechanism for the onset of saturation photocurrent and the reset behavior in the monolayer photodetector is illustrated based on device performances. Electrostatic passivation of interfacial traps is achieved with the bipolar gate pulse and significantly reduces the response time for photocurrent to reach saturated states. This work paves the way toward fast-speed and ultrahigh-gain devices of stacked two-dimensional monolayers.

Single-Grain Gate-All-Around Si Nanowire FET Using Low-Thermal-Budget Processes for Monolithic Three-Dimensional Integrated Circuits.

We introduce a single-grain gate-all-around (GAA) Si nanowire (NW) FET using the location-controlled-grain technique and several innovative low-thermal budget processes, including green nanosecond laser crystallization, far-infrared laser annealing, and hybrid laser-assisted salicidation, that keep the substrate temperature (Tsub) lower than 400 °C for monolithic three-dimensional integrated circuits (3D-ICs). The detailed process verification of a low-defect GAA nanowire and electrical characteristics were investigated in this article. The GAA Si NW FETs, which were intentionally fabricated within the controlled Si grain, exhibit a steeper subthreshold swing (S.S.) of about 65 mV/dec., higher driving currents of 327 µA/µm (n-type) and 297 µA/µm (p-type) @ Vth ± 0.8 V, and higher Ion/Ioff (>105 @|Vd| = 1 V) and have a narrower electrical property distribution. In addition, the proposed Si NW FETs with a GAA structure were found to be less sensitive to Vth roll-off and S.S. degradation compared to the omega(Ω)-gate Si FETs. It enables ultrahigh-density sequentially stackable integrated circuits with superior performance and low power consumption for future mobile and neuromorphic applications.

Neat poly(ortho-methoxyaniline) electrospun nanofibers for neural stem cell differentiation.

In this manuscript, neat electrospun poly(o-methoxyaniline) (POMA) fibers were applied for the first time in the growth of neural stem cells. POMA was synthesized by chemical oxidative polymerization, followed by dissolving in tetrahydrofuran/dimethylformamide to prepare electrospinning solution. Subsequently, the solution was electrospun to produce polymeric fibers. The structure, transparency and morphology of as-prepared POMA fibers were characterized by Fourier transform infrared spectroscopy, UV-visible spectroscopy and scanning electron microscopy, respectively. It was found to have no adverse effects on the long-term proliferation of the neural stem cells (NSCs), retain the ability to self-renew, and exhibit multipotentiality. Studies on cell-fiber interactions were carried out by culturing NSCs on the POMA substrate and assessing their growth, cell viability, and differentiation. Results of cell viability assay, immunofluorescence staining, quantitative real-time reverse transcription-PCR and calcium image studies confirmed that POMA electrospun fibers not only showed better NSCs attachment, but also enhanced and accelerated differentiation.