Surface leakage current analysis of ion implanted ZnS-passivated n-on-p HgCdTe diodes in weak inversion

Effects of fixed charge on R₀A value of ZnS-passivated x=0.3 HgCdTe n-on-p diode are explained as a shunt resistance that affects current-voltage (I-V) and dynamic resistance-voltage (Rd-V) characteristics. The fixed charge of 1×10¹¹/cm² to 2 × 10¹¹/cm² which is usually obtained with ZnS passivation makes the surface weakly inverted and reduces HgCdTe diode R₀A value owing to the short generation lifetime of HgCdTe substrate. The gate-controlled diode and specially fabricated diode are used to explain the surface leakage current in the weak inversion and charge sheet model is used to explain the characteristics. It is found that the surface leakage current by the inverted channel in the weak inversion can reduce R₀A more than other currents such as the generation current and tunneling current which are usually used to explain the surface leakage current of HgCdTe diode.     

The leakage current improvement in an ultrashallow junction NMOSwith Co silicided source and drain

The leakage current characteristics of the cobalt silicided NMOS transistors with a junction depth of 800 Å have been studied. In order to minimize the junction leakage current, the thickness of the CoSi₂ layer should he controlled under 300 Å and the Si surface damage induced by the gate spacer etch should be minimized. The post furnace annealing after the second silicidation by the rapid thermal annealing (RTA) process also affected the leakage current characteristics. The gate induced drain leakage (GIDL) current was not affected by the lateral encroachment of CoSi₂ layer into the channel direction when the gate spacer length was larger than 400 Å     

On the mechanism for interface trap generation in MOS transistorsdue to channel hot carrier stressing

The classical concept and theory suggest that the degradation of MOS transistors is caused by interface trap generation resulting from “hot carrier injection.” We report three new experiments that use the deuterium isotope effect to probe the mechanism for interface trap generation in n-MOS transistors in the presence of hot hole and electron injection. These experiments show clearly that hot carrier injection into the gate oxide exhibits essentially no isotope effect, whereas channel hot electrons at the interface exhibit a large isotope effect. This leads to the conclusion that channel hot electrons, not carriers injected into the gate oxide, are primarily responsible for interface trap generation for standard hot carrier stressing     

Two efficient algorithms for the analyses of a nonlinearly loadedantenna and antenna array in the frequency domain

In this paper, two efficient algorithms for the steady-state scattering responses of a nonlinearly loaded antenna and antenna array in the frequency domain are studied. One is the reflection algorithm (RA), and the other is the inexact Newton approach (INA). The analysis is equivalent to a nonlinear circuit problem with the circuit parameters of antenna element obtained by the moment method. This equivalent nonlinear circuit is then solved using the RA or the INA. In general, the RA is suitable to strongly nonlinearly circuit element. While the INA is suitable for multifrequency excitation. In dealing with the nonlinearly loaded antenna array, the infinite periodic structure Green's function, including the array mutual coupling effects, is applied to simplify the analysis. Both of the two algorithms are easy to be combined with the periodic Green's function to deal with the large nonlinearly loaded antenna array problem     

Impact of Ni concentration on the intermetallic compound formation and brittle fracture strength of Sn–Cu–Ni (SCN) lead-free solder joints

Cu₆Sn₅ and Cu₃Sn are common intermetallic compounds (IMCs) found in Sn–Ag–Cu (SAC) lead-free solder joints with OSP pad finish. People typically attributed the brittle failure to excessive growth of IMCs at the interface between the solder joint and the copper pad. However, the respective role of Cu₆Sn₅ and Cu₃Sn played in the interfacial fracture still remains unclear. In the present study, various amounts of Ni were doped in the Sn–Cu based solder. The different effects of Ni concentration on the growth rate of (Cu, Ni)₆Sn₅/Cu₆Sn₅ and Cu₃Sn were characterized and compared. The results of characterization were used to evaluate different growth rates of (Cu, Ni)₆Sn₅ and Cu₃Sn under thermal aging. The thicknesses of (Cu, Ni)₆Sn₅/Cu₆Sn₅ and Cu₃Sn after different thermal aging periods were measured. High speed ball pull/shear tests were also performed. The correlation between interfacial fracture strength and IMC layer thicknesses was established.     

Outstanding Low-Temperature Performance of Structure-Controlled Graphene Anode Based on Surface-Controlled Charge Storage Mechanism

The energy and power performance of lithium (Li)-ion batteries is significantly reduced at low-temperature conditions, which is mainly due to the slow diffusion of Li-ions in graphite anode. Here, it is demonstrated that the effective utilization of the surface-controlled charge storage mechanism through the transition from layered graphite to 3D crumpled graphene (CG) dramatically improves the Li-ion charge storage kinetics and structural stability at low-temperature conditions. The structure-controlled CG anode prepared via a one-step aerosol drying process shows a remarkable rate-capability by delivering ≈206 mAh g^–1 at a high current density of 10 A g^–1 at room temperature. At an extremely low temperature of −40 °C, CG anode still exhibits a high capacity of ≈154 mAh g^–1 at 0.01 A g^–1 with excellent rate-capability and cycling stability. A combination of electrochemical studies and density functional theory (DFT) reveals that the superior performance of CG anode stems from the dominant surface-controlled charge storage mechanism at various defect sites. This study establishes the effective utilization of the surface-controlled charge storage mechanism through structure-controlled graphene as a promising strategy to improve the charge storage kinetics and stability under low-temperature conditions.     

Hydrogel Microcapsules with a Thin Oil Layer: Smart Triggered Release via Diverse Stimuli

A hydrogel microcapsule with an intermediate thin oil layer is presented to achieve smart release of a broad range of cargoes triggered via diverse stimuli. A microfluidic technique is used to produce triple emulsion droplets with a thin oil layer that separates the innermost aqueous phase from the hydrogel prepolymer phase, which transforms into a hydrogel shell via photopolymerization. The intermediate oil layer within the hydrogel microcapsule acts as an effective diffusion barrier, allowing encapsulation of various small cargoes within a porous hydrogel shell until a stimulus is applied to destabilize the oil layer. It is demonstrated that diverse stimuli including chemical dissolution, mechanical stress, and osmotic pressure can be utilized to release the encapsulated cargo on-demand. In addition, osmotic pressure and the hydrogel shell thickness can be independently tuned to control the onset time of release as well as the release behavior of multi-cargo encapsulated hydrogel microcapsule. The release can be either simultaneous or selective.     

Noncentrosymmetric Tetrel Pnictides RuSi4P4 and IrSi3P3: Nonlinear Optical Materials with Outstanding Laser Damage Threshold

Noncentrosymmetric (NCS) tetrel pnictides have recently generated interest as nonlinear optical (NLO) materials due to their second harmonic generation (SHG) activity and large laser damage threshold (LDT). Herein nonmetal-rich silicon phosphides RuSi₄P₄ and IrSi₃P₃ are synthesized and characterized. Their crystal structures are reinvestigated using single crystal X-ray diffraction and ²⁹Si and ³¹P magic angle spinning NMR. In agreement with previous report RuSi₄P₄ crystallizes in NCS space group P1, while IrSi₃P₃ is found to crystallize in NCS space group Cm, in contrast with the previously reported space group C2. A combination of DFT calculations and diffuse reflectance measurements reveals RuSi₄P₄ and IrSi₃P₃ to be wide bandgap (E_g) semiconductors, E_g = 1.9 and 1.8 eV, respectively. RuSi₄P₄ and IrSi₃P₃ outperform the current state-of-the-art infrared SHG material, AgGaS₂, both in SHG activity and laser inducer damage threshold. Due to the combination of high thermal stabilities (up to 1373 K), wide bandgaps (≈2 eV), NCS crystal structures, strong SHG responses, and large LDT values, RuSi₄P₄ and IrSi₃P₃ are promising candidates for longer wavelength NLO materials.     

Progressive NO2 Sensors with Rapid Alarm and Persistent Memory-Type Responses for Wide-Range Sensing Using Antimony Triselenide Nanoflakes

Antimony triselenide (Sb₂Se₃) nanoflake-based nitrogen dioxide (NO₂) sensors exhibit a progressive bifunctional gas-sensing performance, with a rapid alarm for hazardous highly concentrated gases, and an advanced memory-type function for low-concentration (<1 ppm) monitoring repeated under potentially fatal exposure. Rectangular and cuboid shaped Sb₂Se₃ nanoflakes, comprising van der Waals planes with large surface areas and covalent bond planes with small areas, can rapidly detect a wide range of NO₂ gas concentrations from 0.1 to 100 ppm. These Sb₂Se₃ nanoflakes are found to be suitable for physisorption-based gas sensing owing to their anisotropic quasi-2D crystal structure with extremely enlarged van der Waals planes, where they are humidity-insensitive and consequently exhibit an extremely stable baseline current. The Sb₂Se₃ nanoflake sensor exhibits a room-temperature/low-voltage operation, which is noticeable owing to its low energy consumption and rapid response even under a NO₂ gas flow of only 1 ppm. As a result, the Sb₂Se₃ nanoflake sensor is suitable for the development of a rapid alarm system. Furthermore, the persistent gas-sensing conductivity of the sensor with a slow decaying current can enable the development of a progressive memory-type sensor that retains the previous signal under irregular gas injection at low concentrations.     

Photoactive Electro-Controlled Visual Perception Memory for Emulating Synaptic Metaplasticity and Hebbian Learning

In bionic technology, it has become an innovative process imitating the functionality and structuralism of human biological systems to exploit advanced artificial intelligent machines. Bionics plays a significant role in environmental protection, especially for its low energy loss. By fusing the concept of receptor-like sensing component and synapse-like memory, the photoactive electro-controlled optical sensory memory (PE-SM) is proposed and realized in a single device, which endows a simple methodology of reducing power consumption by photoactive electro-control. The PE-SM is the system built with the stacked atomically thick materials, in which rhenium diselenide serves as a robust photosensor, hexagonal boron nitride serves as a tunneling dielectric, and graphene serves as a charge-storage layer. With the features of the PE-SM, it performs synaptic metaplasticities under optical spikes. In addition, a simulated spiking neural network composed of 24 × 24 PE-SMs is further presented in an unsupervised machine learning environment, performing image recognition via the Hebbian rule. The PE-SM not only improves the neuromorphic computing efficiency but also simplifies the circuit-size structure. Eventually, the concept of photoactive electro-control can extend to other photosensitive 2D materials and provide a new approach of constructing either visual perception memory or photonic synaptic devices.