2.83-kV double-layered NiO/β-Ga_(2)O_(3) vertical p-n heterojunction diode with a power figure-of-merit of 5.98 GW/cm^(2)

This work demonstrates high-performance NiO/β-Ga_(2)O_(3) vertical heterojunction diodes(HJDs)with double-layer junc-tion termination extension(DL-JTE)consisting of two p-typed NiO layers with varied lengths.The bottom 60-nm p-NiO layer fully covers theβ-Ga_(2)O_(3) wafer,while the geometry of the upper 60-nm p-NiO layer is 10μm larger than the square anode elec-trode.Compared with a single-layer JTE,the electric field concentration is inhibited by double-layer JTE structure effectively,resulting in the breakdown voltage being improved from 2020 to 2830 V.Moreover,double p-typed NiO layers allow more holes into the Ga_(2)O_(3) drift layer to reduce drift resistance.The specific on-resistance is reduced from 1.93 to 1.34 mΩ·cm^(2).The device with DL-JTE shows a power figure-of-merit(PFOM)of 5.98 GW/cm^(2),which is 2.8 times larger than that of the conven-tional single-layer JTE structure.These results indicate that the double-layer JTE structure provides a viable way of fabricating high-performance Ga_(2)O_(3) HJDs.

Theoretical foundations of triboelectric nanogenerators(TENGs)

Triboelectric nanogenerator(TENG) is an emerging powerful technology for converting ambient mechanical energy into electrical energy through the effect of triboelectricity. Starting from the expanded Maxwell’s equations, the theoretical framework of TENGs has been gradually established. Here, a review is given about its recent progress in constructing of this general theory. The fundamental mechanism of TENGs is constructed by the driving force—Maxwell’s displacement current, which is essentially different from that of electromagnetic generators. Theoretical calculations of the displacement current from a threedimensional mathematical model are presented, as well as the theoretical studies on the TENGs according to the capacitor models. Furthermore, the figure-of-merits and standards for quantifying the TENG’s output characteristics are discussed, which will provide important guidelines for optimizing the structure and performance of TENGs toward practical applications. Finally,perspectives and challenges are proposed about the basic theory of TENGs and its future technology development.

Low-cost polymer acceptors with noncovalently fused-ring backbones for efficient all-polymer solar cells

The polymerization of fused-ring acceptors(FRAs) to afford their corresponding polymeric acceptors for high-performance all-polymer solar cells(all-PSCs) has achieved remarkable progress in the past few years.However,due to the high degree of synthetic complexity for the monomer,the high-cost of these polymeric acceptors may limit their commercial applications.Thus,it is urgent to develop inexpensive and high-performance polymeric acceptors for all-PSCs.Herein,two novel polymeric acceptors(PBTzO and PBTzO-2F) have been designed and synthesized by copolymerization of noncovalently fused ring acceptors(NFRAs),which were employed in all-PSCs for the first time.Upon introducing the “noncovalently conformational locks(NoCLs)” in the backbone and selective fluorination of the end-group,photophysical and electrical properties,and solidstate packing properties of the NFRAs have been rationally tuned.As a result,the PBDB-T:PBTzO-2F based devices presented an excellent power conversion efficiency(PCE) of 11.04%,much higher than that of PBTzO based ones due to the increased charge generation and extraction,improved hole transfer and carrier mobilities,and reduced energy loss.More importantly,PBTzO-2F exhibited a much lower synthetic complexity(SC) index and higher figure-of-merit(FOM) values than the high-performance fused-ring acceptor based polymer acceptors(FRA-PAs) due to the simpler structures and more effective synthesis.This contribution provided a novel idea to achieve low-cost and high-performance all-PSCs.

An 8-bit 100-MS/s pipelined ADC without dedicated sample-and-hold amplifier

An 8-b 100-MS/s pipelined analog-to-digital converter（ADC） is presented.Without the dedicated sample-and -hold amplifier（SHA）,it achieves figure-of-merit and area 21%and 12%less than the conventional ADC with the dedicated SHA,respectively.The closed-loop bandwidth of op amps in multiplying DAC is modeled,providing guidelines for power optimization.The theory is well supported by transistor level simulations.A 0.18-μm 1P6M CMOS process was used to integrate the ADCs,and the measured results show that the effective number of bits is 7.43 bit and 6.94 bit for 1-MHz and 80-MHz input signal,respectively,at 100 MS/s.The power dissipation is 23.4 mW including voltage/current reference at 1.8-V supply,and FoM is 0.85 pJ/step.The ADC core area is 0.53 mm^2.INL is -0.99 to 0.76 LSB,and DNL is -0.49 to 0.56 LSB.

The dielectric studies on sol–gel routed molybdenum oxide thin film

The influence of temperature on the dielectric properties of sol-gel routed spin-coated molybdenum trioxide(MoO_(3)) thin film has been investigated.Prepared films were annealed at temperatures 250℃,350℃ and 400℃.The phase transformation from amorphous to
-orthorhombic phase with preferential orientation(022)has been found by XRD for the film annealed above 250℃.The vibration modes of
-orthorhombic MoO_(3) have been examined by Raman spectrum.The predominant Raman's band of
-orthorhombic MoO_(3) thin film has been found at the frequency range 1000–600 cm^(-1).Using the UV–Vis spectrum,the band gap of the film is found to be 3.3–3.8 eV.The surface morphology of the MoO_(3) films has been examined by scanning electron microscope.The AC conductivity measurement of the MoO_(3) film has been carried out in the frequency range 10–10^(6) Hz.The frequency dependence of the impedance has been plotted in the complex plane.The variation of the capacitance and dielectric constant of MoO_(3) film with respect to temperature and frequency has been analyzed.Tunability of capacitance and figure of merit of the film are also determined.