Kang Jinfeng

Phonon-Limited Electron Mobility in Single-Layer MoS2

The dynamics of electron transport in single-layer MoS2 is simulated by employing the single particle Monte Carlo method. Acoustic phonon scattering, optical phonon scattering and Frohlich scattering are taken into account. It is found that the electron mobility decreases from 806 cm2/Vs for a transverse electrical field of 103 V/m to 426/112 cm2/Vs for a transverse electrical field of 105/107 V/m. Further detailed analysis on carrier dynamics reveals that the low field mobility is dominated by the acoustic phonon scattering while the role of optical phonon scattering is to relax the electron energy below the optical phonon energy by efficient energy relaxation through optical phonon emission. Only when the transverse electrical field is larger than 106 V/m, the mobility can be determined by the optical phonon scattering, leading to a strong mobility degradation.

Improved Resistive Switching Characteristics of Ag-Doped ZrO2 Films Fabricated by Sol-Gel Process

Ag-doped and pure ZrO2 thin films are prepared on Pt/Ti/SiO2/Si substrates by sol-gel process for resistive random access memory application. The highly reproducible resistive switching is achieved in the 10% Ag-doped ZrO2 devices. The improved resistive switching behaviour in the Ag doped ZrO2 devices could be attributed to Ag doping effect on the formation of the stable filamentary conducting paths. In addition, dual-step reset processes corresponding to three stable resistance states are observed in the 10% Ag doped ZrO2 devices, which may be implemented for the application of multi-bit storage.

The influence of thermally assisted tunneling on the performance of charge trapping memory

We evaluate the influence of the thermally assisted tunneling (TAT) mechanism on charge trapping memory (CTM) cell performance by numerical simulation, and comprehensively analyse the effects of the temperature, trap depth, distribution of trapped charge, gate voltage and parameters of TAT on erasing/programming speed and retention performance. TAT is an indispensable mechanism in CTM that can increase the detrapping probability of trapped charge. Our results reveal that the TAT effect causes the sensitivity of cell performance to temperature and it could affect the operational speed, especially for the erasing operation. The results show that the retention performance degrades compared with when the TAT mechanism is ignored.We evaluate the influence of the thermally assisted tunneling (TAT) mechanism on charge trapping memory (CTM) cell performance by numerical simulation, and comprehensively analyse the effects of the temperature, trap depth, distribution of trapped charge, gate voltage and parameters of TAT on erasing/programming speed and retention performance. TAT is an indispensable mechanism in CTM that can increase the detrapping probability of trapped charge. Our results reveal that the TAT effect causes the sensitivity of cell performance to temperature and it could affect the operational speed, especially for the erasing operation. The results show that the retention performance degrades compared with when the TAT mechanism is ignored.

Effect of trapped charge accumulation on the retention of charge trapping memory

The accumulation process of trapped charges in a TANOS cell during P/E cycling is investigated via numerical simulation. The recombination process between trapped charges is an important issue on the retention of charge trapping memory. Our results show that accumulated trapped holes during P/E cycling can have an influence on retention, and the recombination mechanism between trapped charges should be taken into account when evaluating the retention capability of TANOS.

Carriers recombination processes in charge trapping memory cell by simulation

We have evaluated the effects of recombination processes in a charge storage layer, either between trapped electrons and trapped holes or between trapped carriers and free carriers, on charge trapping memory cells performances by numerical simulation. Recombination is an indispensable mechanism in charge trapping memory. It helps charge convert process between negative and positive charges in the charge storage layer during charge trapping memory programming/erasing operation. It can affect the speed of programming and erasing operations.

Fabrication and characteristics of high-K HfO2 gate dielectrics on n-germanium

This paper reports that the high-K HfO2 gate dielectrics are fabricated on n-germanium substrates by sputtering Hf on Ge and following by a furnace annealing. The impacts of sputtering ambient, annealing ambient and annealing temperature on the electrical properties of high-K HfO2 gate dielectrics on germanium substrates are investigated. Experimental results indicate that high-K HfO2 gate dielectrics on germanium substrates with good electrical characteristics are obtained, the electrical properties of high-K HfO2 gate dielectrics is strongly correlated with sputtering ambient, annealing ambient and annealing temperature.

Annealing characteristics of ultra-thin high-K HfO2 gate dielectrics

Ultra-thin HfO2 gate-dielectric films were fabricated by ion-beam sputtering a sintered HfO2 target and subsequently annealed at different temperatures and atmospheres. We have studied the capacitance-voltage, current-voltage and breakdown characteristics of the gate dielectrics. The results show that electrical characteristics of HfO2 gate dielectric are related to the annealing temperature. With increase annealing temperature, the largest value of capacitance decreases, the equivalent oxide thickness increases, the leakage current reduces and the breakdown voltage decreases.

A physical-based pMOSFETs threshold voltage model including the STI stress effect

The physical threshold voltage model of pMOSFETs under shallow trench isolation (STI) stress has been developed. The model is verified by 130 nm technology layout dependent measurement data. The comparison between pMOSFET and nMOSFET model simulations due to STI stress was conducted to show that STI stress induced less threshold voltage shift and more mobility shift for the pMOSFET. The circuit simulations of a nine stage ring oscillator with and without STI stress proved about 11% improvement of average delay time. This indicates the importance of STI stress consideration in circuit design.

Different interdiffusion characteristics between Ag/YBa2Cu3O7−x and Al/YBa2Cu3O7−x contact interfaces

Abstract The differences between the interdiffusion characteristics of Ag YBa 2 Cu 3 O 7−x and Al YBa 2 Cu 3 O 7−x contact interfaces have been revealed by secondary ion mass spectrometry (SIMS). The different electrical properties of Ag YBa 2 Cu 3 O 7−x and YBa2Cu3O7−x films after high temperature treatment are well understood by the SIMS results.

Degradation Characteristics of Resistive Switching Memory Devices Correlated with Electric Field Induced Ion-Migration Effect of Anode

The electrode effect of resistive switching memory devices on resistive switching behaviors is studied. Compared to TiN- or Ti-electrode devices, significantly reduced switching parameters such as resistance-ratio of high- and low-resistance states and set-voltage are observed experimentally in the Al-electrode devices when a positive voltage bias is applied to the Al-electrode during the forming process. An electric-field induced metal-ion-migration effect is proposed to elucidate the observed electrode dependence of the resistive switching behaviors in the resistive switching memory devices. The further measured data identify the validity of the proposed mechanism.