Based on white light emission at silicon (Si)/ZnO hetrerojunction, a pressure-sensitive Si/ZnO nanowires heterostructure matrix light emitting diode (LED) array is developed. The light emission intensity of a single heterostructure LED is tuned by external strain: when the applied stress keeps increasing, the emission intensity first increases and then decreases with a maximum value at a compressive strain of 0.15-0.2%. This result is attributed to the piezo-phototronic effect, which can efficiently modulate the LED emission intensity by utilizing the strain-induced piezo-polarization charges. It could tune the energy band diagrams at the junction area and regulate the optoelectronic processes such as charge carriers generation, separation, recombination, and transport. This study achieves tuning silicon based devices through piezo-phototronic effect.

Large-scale simulations are performed by means of the transfer-matrix method to reveal optimal conditions for metal–dielectric core–shell particles to induce the largest fluorescence on their surfaces. With commonly used plasmonic cores (Au and Ag) and dielectric shells (SiO2, Al2O3, ZnO), optimal core and shell radii are determined to reach maximum fluorescence enhancement for each wavelength within 550–850 nm (Au core) and 390–500 nm (Ag core) bands, in both air and aqueous hosts. The peak value of the maximum achievable fluorescence enhancement factors of core–shell nanoparticles, taken over an entire wavelength interval, increases with the shell refractive index and can reach values up to 9 and 70 for Au and Ag cores, within 600–700 and 400–450 nm wavelength ranges, respectively, which is much larger than that for corresponding homogeneous metal nanoparticles. Replacing air by an aqueous host has a dramatic effect of nearly halving the sizes of optimal core–shell configurations at the peak value of the maximum achievable fluorescence. In the case of Au cores, the fluorescence enhancements for wavelengths within the first near-infrared biological window (NIR-I) between 700 and 900 nm can be improved 2-fold compared to a homogeneous Au particle when the shell refractive index is n s ≳ 2. As a rule of thumb, the wavelength region of optimal fluorescence (maximal nonradiative decay) turns out to be red-shifted (blue-shifted) by as much as 50 nm relative to the localized surface plasmon resonance wavelength of the corresponding optimized core–shell particle. Our results provide important design rules and general guidelines for enabling versatile platforms for imaging, light source, and biological applications.

Power dissipation is a fundamental issue for future chip-based electronics. As promising channel materials, two-dimensional semiconductors show excellent capabilities of scaling dimensions and reducing off-state currents. However, field-effect transistors based on two-dimensional materials are still confronted with the fundamental thermionic limitation of the subthreshold swing of 60 mV decade−1 at room temperature. Here, we present an atomic threshold-switching field-effect transistor constructed by integrating a metal filamentary threshold switch with a two-dimensional MoS2 channel, and obtain abrupt steepness in the turn-on characteristics and 4.5 mV decade−1 subthreshold swing (over five decades). This is achieved by using the negative differential resistance effect from the threshold switch to induce an internal voltage amplification across the MoS2 channel. Notably, in such devices, the simultaneous achievement of efficient electrostatics, very small sub-thermionic subthreshold swings, and ultralow leakage currents, would be highly desirable for next-generation energy-efficient integrated circuits and ultralow-power applications.