Quantitative measurement of the charge carrier concentration using dielectric force microscopy

The charge carrier concentration profile is a critical factor that determines semiconducting material properties and device performance.Dielectric force microscopy(DFM)has been previously developed to map charge carrier concentrations with nanometer-scale spatial resolution.However,it is challenging to quantitatively obtain the charge carrier concentration,since the dielectric force is also affected by the mobility.Here,we quantitative measured the charge carrier concentration at the saturation mobility regime via the rectification effect-dependent gating ratio of DFM.By measuring a series of n-type GaAs and GaN thin films with mobility in the saturation regime,we confirmed the decreased DFM-measured gating ratio with increasing electron concentration.Combined with numerical simulation to calibrate the tip–sample geometry-induced systematic error,the quantitative correlation between the DFM-measured gating ratio and the electron concentration has been established,where the extracted electron concentration presents high accuracy in the range of 4×10^(16)–1×10^(18)cm^(-3).We expect the quantitative DFM to find broad applications in characterizing the charge carrier transport properties of various semiconducting materials and devices.

Low-Enthalpy and High-Entropy Polymer Electrolytes for Li-Metal Battery

lonic-conductive solid-state polymer electrolytes are promising for the development of advanced lithium batteries yet a deeper understanding of their underlying ion-transfer mechanism is needed to improve performance.Here we demonstrate the low-enthalpy and high-entropy(LEHE)electrolytes can intrinsically generate remarkably free ions and high mobility,enabling them to efficiently drive lithium-ion storage.The LEHE electrolytes are constructed on the basis of introducing CsPbl_(3)perovskite quantum dots(PQDs)to strengthen PEO@LiTFSI complexes.An extremely stable cycling>1000 h at 0.3 mA cm^(-2)can be delivered by LEHE electrolytes.Also,the as-developed Li|LEHE|LiFePO_(4)cell retains 92.3%of the initial capacity(160.7 mAh g^(-1))after 200 cycles.This cycling stability is ascribed to the suppressed charge concentration gradient leading to free lithium dendrites.It is realized by a dramatic increment in lithium-ion transference number(0.57 vs 0.19)and a significant decline in ion-transfer activation energy(0.14 eV vs 0.22 eV)for LEHE electrolytes comparing with PEO@LiTFSI counterpart.The CsPbl_(3)PQDs promote highly structural disorder by inhibiting crystallization and hence endow polymer electrolytes with low melting enthalpy and high structural entropy,which in turn facilitate long-term cycling stability and excellent rate-capability of lithium-metal batteries.

Characteristics and mechanisms of strain waves generated in rock by cylindrical explosive charges

A superposing principle, by suitably adding the strain waves from a number of concentrated explosive charges to approximate the waves generated by a cylindrical charge based on the strain wave of a point or small spherical explosive charge generated in rock, is used to further study the triggering time of strain gauges installed in radial direction at same distances but different positions surrounding a cylindrical explosive charge in rock. The duration of the first compression phase and peak value of strain wave, and furthermore, their differences are analyzed and some explanations are given. Besides that, the gauge orientation in which the maximum peak value occurs is also discussed. At last, the effect of velocity of detonation(V.O.D.) of a cylindrical explosive charge on the strain waves generated in the surrounding rock is taken as key research and the pattern of peak amplitude of a strain wave varies with the V.O.D. is likely to have been found.

Computational exploration and screening of novel Janus MA2Z4 (M = Sc–Zn, Y–Ag, Hf–Au;A=Si, Ge;Z=N, P) monolayers and potential application as a photocatalyst

By high-throughput calculations,13 thermally and environmentally stable Janus MA_(2)Z_(4) monolayers were screened from 104 types of candidates.The 13 stable monolayers have very high charge carrier concentrations(×10^(15) cm^(–2)),which are better than those of the well-known graphene and TaS_(2).Because of their excellent conductivity,the 6 monolayers with band gaps less than 0.5 eV are identified as potential electrode materials for hydrogen evolution reaction applications.For potential applications as photoelectric or photocatalytic materials,bandgaps(Eg-HSE)higher than 0.5 eV remained,which resulted in 7 potential candidates.Based on optical absorption analysis in the visible-light range,H-HfSiGeP_(4) and HMoSiGeP_(4) have higher absorption ability and optical conductivity,which is quite impressive for optoelectronic,solar cell device,and photocatalysis applications.Additionally,the transmittance coefficient of Janus MA_(2)Z_(4) monolayers is approximately 70%–80%in the visible-light range,which implies that these monolayers show good light transmittance.For potential applications as photocatalysts,the redox potential and charge effective mass analysis indicate that H-HfSiGeP_(4),HMoSiGeP_(4),T-ScSiGeN_(4),and T-ZrSiGeN_(4) are suitable photocatalysts for CO_(2) reduction reactions.Using high-throughput identification,13 types of new and stable Janus MA2Z4 monolayers were explored,and the basic properties and potential applications were investigated,which can reduce the time for experiments and provide basic data for the material genome initiative.