We have investigated strong optical nonlinearity of monolayer MoS2(1–x)Se2x across the exciton resonance, which is directly tunable by Se doping. The quality of monolayer alloys prepared by chemical vapor deposition is verified by atomic force microscopy, Raman spectroscopy, and photoluminescence analysis. The crystal symmetry of all of our alloys is essentially D 3h , as confirmed by polarization-dependent second-harmonic generation (SHG). The spectral structure of the exciton resonance is sampled by wavelength-dependent SHG (λ = 1000–1800 nm), where the SHG resonance red-shifts in accordance with the corresponding optical gap. Surprisingly, the effect of compositional variation turns out to be much more dramatic owing to the unexpected increase of B-exciton-induced SHG, which indeed dominates over the A-exciton resonance for x ≥ 0.3. The overall effect is therefore stronger and broader SHG resonance where the latter arises from different degrees of red-shift for the two exciton states. We report the corresponding absolute SHG dispersion of monolayer alloys, χ(2), as a function of Se doping. We believe that our finding is a critical step toward engineering highly efficient nonlinear optical van der Waals materials working in a broader performance range.

Lithium sulfur (Li–S) batteries represent a promising future battery technology. However, the low electrical conductivity of solid-state sulfur species (S, Li2S2, and Li2S) and the polysulfide shuttle effect deteriorate their practical capacity and cycling retention. Herein, we present an interlayer composed of magnesium oxide (MgO) nanoparticles and carbon matrix for the Li–S batteries. In the composite, MgO can capture dissolved polysulfides that diffuse to the carbon matrix along the oxide surface for further reduction reactions. As a novel precursor to produce the composite structure, a Mg metal–organic-framework, Mg-MOF-74, is adopted and synthesized on a free-standing carbon paper (MOF/C-paper). Through pyrolysis, Mg-MOF-74 is converted into highly porous carbon containing uniformly distributed MgO nanoparticles (MgO@C/C-paper). The Li–S cells assembled with MgO@C/C-paper and C-paper interlayer show significantly higher initial capacities (980 and 898 mAh g–1, respectively) than the interlayer-free cell (729 mAh g–1) owing to the conductive interlayers. After 200 cycles at 0.2 C, the MgO@C/C-paper cell presents a cycle retention (78.3%) superior to that of the C-paper cell (76.5%). With a higher sulfur loading of 3.3 mg cm–2, the MgO@C/C-paper cell exhibits an even higher capacity retention (80.1%) than the C-paper cell (54.6%) after 100 cycles. The excellent cycle stability of the MgO@C/C-paper cell over the C-paper cell demonstrates that the unique structure of the MOF-derived MgO@C is highly effective in anchoring and reutilizing dissolved polysulfides.

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To verify the effects of process conditions for the TFTs employing In−Ga−Zn-O (IGZO) channels prepared by atomic layer deposition (ALD), such as cationic composition of channel and/or source/drain (S/D) electrodes, the device characteristics including the field-effect mobility (μ FE ), the contact resistance (R C ), and the channel length deviation (ΔL) were systematically investigated for the ALD IGZO thin film transistors (TFTs) fabricated with controlling the ALD subcyclic ratios and with variations in S/D electrodes of indium−tin-oxide (ITO) and molybdenum (Mo). The ALD temperature was fixed at 200 °C. When the subcyclic ratios of precursors (triethyl indium: In−Ga bimetallic: diethyl zinc) were modulated to 0:2:2, 1:2:2, and 2:2:2, the cationic compositions (In:Ga:Zn) were determined to be 1.

This paper presents a high-uniformity post-CMOS fabricated uncooled microbolometer focal plane array (MFPA) integrated with an active matrix circuit. The active matrix circuit selects the row and column of MFPA, calibrates output offset and gain, and converts the resistance changes of MFPA to the output currents. The active matrix circuit with column-wise transistor-sharing scheme is proposed to improve the output non-uniformity. The output non-uniformity with proposed scheme is reduced to 26 %, compared to the conventional scheme.