Low-resistance ohmic contacts on InAlN/GaN heterostructures with MOCVD-regrown n+-InGaN and mask-free regrowth process

This paper studied the low-resistance ohmic contacts on InAlN/GaN with metal–organic chemical vapor deposition(MOCVD)regrowth technique.The 150-nm regrown n-InGaN exhibits a low sheet resistance of 31Ω/□,resulting in an extremely low contact resistance of 0.102Ω·mm between n^(+)-InGaN and InAlN/GaN channels.Mask-free regrowth process was also used to significantly improve the sheet resistance of InAlN/GaN with MOCVD regrown ohmic contacts.Then,the diffusion mechanism between n^(+)-InGaN and InAlN during regrowth process was investigated with electrical and structural characterizations,which could benefit the further process optimization.

Effects of pulsed magnetic field on density reduction of high flow velocity plasma sheath

A three-dimensional model is proposed in this paper to study the effect of the pulsed magnetic field on the density distribution of high flow velocity plasma sheath.Taking the typical parameters of plasma sheath at the height of 71 km as an example,the distribution characteristics and time evolution characteristics of plasma density in the flow field under the action of pulsed magnetic field,as well as the effect of self-electric field on the distribution of plasma density,are studied.The simulation results show that pulsed magnetic field can effectively reduce the density of plasma sheath.Meanwhile,the simulation results of three-dimensional plasma density distribution show that the size of the density reduction area is large enough to meet the communication requirements of the Global Position System(GPS)signal.Besides,the location of density reduction area provides a reference for the appropriate location of antenna.The time evolution of plasma density shows that the effective density reduction time can reach 62%of the pulse duration,and the maximum reduction of plasma density can reach 55%.Based on the simulation results,the mechanism of the interaction between pulsed magnetic field and plasma flow field is physically analyzed.Furthermore,the simulation results indicate that the density distributions of electrons and ions are consistent under the action of plasma self-electric field.However,the quasi neutral assumption of plasma in the flow field is not appropriate,because the self-electric field of plasma will weaken the effect of the pulsed magnetic field on the reduction of electron density,which cannot be ignored.The calculation results could provide useful information for the mitigation of communication blackout in hypersonic vehicles.

Enhancing terahertz photonic spin Hall effect via optical Tamm state and the sensing application

The photonic spin Hall effect(PSHE),characterized by two splitting beams with opposite spins,has great potential applications in nano-photonic devices,optical sensing fields,and precision metrology.We present the significant enhancement of terahertz(THz)PSHE by taking advantage of the optical Tamm state(OTS)in In Sb-distributed Bragg reflector(DBR)structure.The spin shift of reflected light can be dynamically tuned by the structural parameters(e.g.the thickness)of the InSb-DBR structure as well as the temperature,and the maximum spin shift for a horizontally polarized incident beam at 1.1 THz can reach up to 11.15 mm.Moreover,we propose a THz gas sensing device based on the enhanced PSHE via the strong excitation of OTS for the InSb-DBR structure with a superior intensity sensitivity of 5.873×10^(4)mm/RIU and good stability.This sensor exhibits two orders of magnitude improvement compared with the similar PSHE sensor based on In Sb-supported THz long-range surface plasmon resonance.These findings may provide an alternative way for the enhanced PSHE and offer the opportunity for developing new optical sensing devices.

High-performance ultrathin Ag electrodes by chemical bond anchoring Ag atoms for stretchable organic light-emitting devices

The progress of stretchable organic light-emitting devices(OLEDs)has brought about new possibilities for highly functional wearable electronics.However,the efficiency and durability of stretchable OLEDs have been limited by the performance of stretchable transparent electrodes.Here,we proposed an interface engineering strategy that involves anchoring the growth of silver(Ag)atoms with amine-enriched biomaterials for high-quality stretchable transparent electrodes.The strong interactions between the Ag atom and the amine group enable the uniform Ag electrodes at an ultralow thickness of 7 nm,and provide remarkable mechanical flexibility and strain endurance to the Ag electrodes.The distinct effects of different amino acids were investigated,and a deep understanding of their unique contributions to the film formation process was gained.The resulting ultrathin Ag electrodes exhibit outstanding optoelectrical properties(transmittance of~98% and sheet resistance of~8.7Ω/sq)and excellent stretchability during 500 stretching cycles at 100%strain.Stretchable green phosphorescent OLEDs based on the Ag electrodes have been demonstrated with a current efficiency of up to~70.4 cd/A.Impressively,the devices show excellent stretching stability,retaining~89% of the original luminance and~78% of the original current efficiency after 200 stretching cycles at 100%strain.This work opens up new possibilities for stretchable transparent electrodes,fostering advancements in wearable displays and other innovative flexible devices.

Surface-tuned two-dimension MXene scaffold for highly reversible zinc metal anode

Zinc metal has aroused increasing interest as anode material of Zn-based batteries for their energy storage application.However,the uneven Zn stripping/plating processes induce severe dendrite growth,leading to low Coulombic efficiency and safety hazards.Herein,a surface-tuned two-dimensional(2D)MXene Ti_(3)C_(2)Tx scaffold as a robust skeleton is developed to facilitate the uniform Zn stripping/plating.The Ti_(3)C_(2)Tx with high electrical conductivity and unique structure provides fast ionic-transport paths,promising even Zn2+stripping/plating processes.With suppressed Zn dendrite growth and uniform nucleation,the proposed 2D Ti_(3)C_(2)Tx scaffold for Zn metal anode delivers a low voltage hysteresis of 63 m V and long lifespan over 280 h.This surface-tuned engineering strategy demonstrates the potential application of Zn anode with MXene skeleton for next-generation Zn-based batteries.

Absence of eigenvalues for quasiperiodic Schrodinger type operators

We obtain the matrix-valued Schrodinger-type operators [Hα,θ] with Lipschitz potentials having no eigenvalues on the set {E : L ( E )<δ)C,d(α,θ),where δ is an explicit function depending on the sampling function C(θ), dimension d, phase θ, and frequency a, and L ( E ) is the Lyapunov exponent.

New proof of continuity of Lyapunov exponents for a class of smooth Schrödinger cocycles with weak Liouville frequencies

We reconsider the continuity of the Lyapunov exponents for a class of smooth Schrödinger cocycles with a C2 cos-type potential and a weak Liouville frequency.We propose a new method to prove that the Lyapunov exponent is continuous in energies.In particular,a large deviation theorem is not needed in the proof.