Oxide Thickness Effects on n-MOSFETs Under On-State Hot-Carrier Stress

Hot carrier induced (HCI) degradation of surface channel n MOSFETs with different oxide thicknesses is investigated under maximum substrate current condition.Results show that the key parameters m and n of Hu's lifetime prediction model have a close relationship with oxide thickness.Furthermore,a linear relationship is found between m and n .Based on this result,the lifetime prediction model can be expended to the device with thinner oxides.

Combined effects of carrier scattering and Coulomb screening on photoluminescence in InGaN/GaN quantum well structure with high In content

Photoluminescence(PL) spectra of two different green InGaN/GaN multiple quantum well(MQW) samples S1 and S2,respectively with a higher growth temperature and a lower growth temperature of InGaN well layers are analyzed over a wide temperature range of 6 K-3 30 K and an excitation power range of 0.001 mW-75 mW.The excitation power-dependent PL peak energy and linewidth at 6 K show that in an initial excitation power range,the emission process of the MQW is dominated simultaneously by the combined effects of the carrier scattering and Coulomb screening for both the samples,and both the carrier scattering effect and the Coulomb screening effect are stronger for S2 than those for S1;in the highest excitation power range,the emission process of the MQWs is dominated by the filling effect of the high-energy localized states for S1,and by the Coulomb screening effect for S2.The behaviors can be attributed to the fact that sample S2 should have a higher amount of In content in the InGaN well layers than S1 because of the lower growth temperature,and this results in a stronger component fluctuation-induced potential fluctuation and a stronger well/barrier lattice mismatchinduced quantum-confined Stark effect.This explanation is also supported by other relevant measurements of the samples,such as temperature-dependent peak energy and excitation-power-dependent internal quantum efficiency.

Switchable PLL Frequency Synthesizer andHot Carrier Effects

In this paper, a new strategy of switchable CMOS phase-locked loop frequency synthesizer is proposed to increase its tuning range. The switchable PLL which integrates two phase-locked loops with different tuning frequencies are designed and fabricated in 0.5 μm n-well CMOS process. Cadence/Spectre simulations show that the frequency range of the switchable phased-locked loop is between 320 MHz to 1.15 GHz. The experimental results show that the RMS jitter of the phase-locked loop changes from 26 ps to 123 ps as output frequency varies. For 700 MHz carrier frequency, the phase noise of the phase-locked loop reaches as low as ?81 dBc/Hz at 10 kHz offset frequency and ?104 dBc/Hz at 1 MHz offset frequency. A device degradation model due to hot carrier effects has been used to analyze the jitter and phase noise performance in an open loop voltage-controlled oscillator. The oscillation frequency of the voltage-controlled oscillator decreases by approximately 100 to 200 MHz versus the bias voltage and the RMS jitter increases by 40 ps under different phase-locked loop output frequencies after 4 hours of stress time.

Effects of atomic number Z on the energy distribution of hot electrons generated by femtosecond laser interaction with metallic targets

The effects of atomic number Z on the energy distribution of hot electrons generated by the interaction of 60fs, 130mJ, 800nm, and 7×10^17W/cm^2 laser pulses with metallic targets have been studied experimentally. The results show that the number and the effective temperature of hot electrons increase with the atomic number Z of metallic targets, and the temperature of hot electrons are in the range of 190-230keV, which is consistent with a scaling law of hot electrons temperature.

Suppressing the hot carrier injection degradation rate in total ionizing dose effect hardened nMOSFETs

Annular gate nMOSFETs are frequently used in spaceborne integrated circuits due to their intrinsic good capability of resisting total ionizing dose （TID） effect. However, their capability of resisting the hot carrier effect （HCE） has also been proven to be very weak. In this paper, the reason why the annular gate nMOSFETs have good TID but bad HCE resistance is discussed in detail, and an improved design to locate the source contacts only along one side of the annular gate is used to weaken the HCE degradation. The good TID and HCE hardened capability of the design are verified by the experiments for I/O and core nMOSFETs in a 0.18 μm bulk CMOS technology. In addition, the shortcoming of this design is also discussed and the TID and the HCE characteristics of the replacers （the annular source nMOSFETs） are also studied to provide a possible alternative for the designers.

Positive Bias Temperature Instability and Hot Carrier Injection of Back Gate Ultra-thin-body In0.53Ga0.47As-on-Insulator n-Channel Metal-Oxide-Semiconductor Field-Effect Transistor

Ultra-thin-body （UTB） In0.53Ga0.47As-on-insulator （In0.53Ga0.47As-OI） structures with thicknesses of 8 and 15nm are realized by transferring epitaxially grown In0.53Ga0.47As layers to silicon substrates with 15-nmthick A12 03 as a buried oxide by using the direct wafer bonding method. Back gate n-channel metal-oxidesemiconductor field-effect transistors （nMOSFETs） are fabricated by using these In0.53Ga0.47As-OI structures with excellent electrical characteristics. Positive bias temperature instability （PBTI） and hot carrier injection （HCI） characterizations are performed for the In0.53Ga0.47As-OI nMOSFETs. It is confirmed that the In0.53Ga0.47 As-OI nMOSFETs with a thinner body thickness suffer from more severe degradations under both PBTI and HCr stresses. Moreover, the different evolutions of the threshold voltage and the saturation current of the UTB In0.53Ga0.47As-OI nMOSFETs may be due to the slow border traps.

Anisotropic Plasmon Resonance Enables Spatially Controlled Photothermal and Photochemical Effects in Hot Carrier-Driven Catalysis

Localized surface plasmon resonance has been demonstrated to provide effective photophysical enhancement mechanisms in plasmonic photocatalysis.However,it remains highly challenging for distinct mechanisms to function in synergy for a collective gain in catalysis due to the lack of spatiotemporal control of their effect.Herein,the anisotropic plasmon resonance nature of Au nanorods was exploited to achieve distinct functionality towards synergistic photocatalysis.Photothermal and photochemical effects were enabled by the longitudinal and transverse plasmon resonance modes,respectively,and were enhanced by partial coating of silica nanoshells and epitaxial growth of a reactor component.Resonant excitation leads to a synergistic gain in photothermal-mediated hot carrier-driven hydrogen evolution catalysis.Our approach provides important design principles for plasmonic photocatalysts in achieving spatiotemporal modulation of distinct photophysical enhancement mechanisms.It also effectively broadens the sunlight response range and increases the efficacy of distinct plasmonic enhancement pathways towards solar energy harvesting and conversion.

Effect of Hot Carrier on Amplitude Modulation and Demodulation of Gaussian High Power Helicon Wave in Homogeneous Longitudinally Magnetized Strain Dependent Dielectric Material

In the present communication, the hydrodynamic model is used to investigate the amplitude modulation as well as demodulation of an electromagnetic wave of high power helicon pump wave into another helicon wave in strain dependent dielectric material incorporating carrier heating (CH) effects. The consideration of CH in modulation and demodulation is prime importance for the adding of new dimension in analysis of amplification of acoustic helicon wave. By using the dispersion relation, threshold pump electric filed and growth rate of unstable mode from the modulation and demodulation of the high power helicon wave well above from the threshold value will be discussed in the present analysis. The numerical analysis is applied to a strain dependent dielectric material, BaTiO3 at room temperature and irradiated with high power helicon wave of frequency 1.78 × 1014 Hz. This material is very sensitive to the pump intensities, therefore during studies, Gaussian shape of the helicon pump wave is considered during the propagation in stain dependent dielectric material and opto-acoustic wave in the form of Gaussian profile (ω0,κ0) is induced longitudinally along the crystallographic plane of BaTiO3. Its variation is caused by the available magnetic field (ωc), interaction length (z) and pulsed duration of interaction (τ). From the analysis of numerical results, the incorporation of CH effect can effectively modify the magnitude of modulation or demodulation of the amplitude of high power helicon laser wave through diffusion process. Not only the amplitude modulation and demodulation of the wave, the diffusion of the CH effectively modifies the growth rate of unstable mode of frequency in BaTiO3. The propagation of the threshold electric field shows the sinusoidal or complete Gaussian profile, whereas this profile is found to be completely lost in growth of unstable mode. It has also been seen that the growth rate is observed to be of the order of 108 - 1010 s-1 but from diffusion of carrier heating, and that its order is enhanced from 1010 - 1012 s-1 with the variation of the magnetized frequency from 1 to 2.5 × 1014 Hz.

Actions of negative bias temperature instability （NBTI） and hot carriers in ultra-deep submicron p-channel metal-oxide-semiconductor field-effect transistors （PMOSFETs）

Hot carrier injection （HCI） at high temperatures and different values of gate bias Vg has been performed in order to study the actions of negative bias temperature instability （NBTI） and hot carriers. Hot-carrier-stress-induced damage at Vg = Vd, where Vd is the voltage of the transistor drain, increases as temperature rises, contrary to conventional hot carrier behaviour, which is identified as being related to the NBTI. A comparison between the actions of NBTI and hot carriers at low and high gate voltages shows that the damage behaviours are quite different： the low gate voltage stress results in an increase in transconductance, while the NBTI-dominated high gate voltage and high temperature stress causes a decrease in transconductance. It is concluded that this can be a major source of hot carrier damage at elevated temperatures and high gate voltage stressing of p-channel metal-oxide-semiconductor field-effect transistors （PMOSFETs）. We demonstrate a novel mode of NBTI-enhanced hot carrier degradation in PMOSFETs. A novel method to decouple the actions of NBTI from that of hot carriers is also presented.

STUDY ON THE RELATION BETWEEN STRUCTURE AND HOT CARRIER EFFECT IMMUNITY FOR DEEP SUB-MICRON GROOVED GATE NMOSFET's

Grooved gate structure Metal-Oxide-Semiconductor (MOS) device is consideredas the most promising candidate used in deep and super-deep sub-micron region, for it cansuppress hot carrier effect and short channel effect deeply. Based on the hydrodynamic energytransport model, using two-dimensional device simulator Medici, the relation between structureparameters and hot carrier effect immunity for deep-sub-micron N-channel MOSFET's is studiedand compared with that of counterpart conventional planar device in this paper. The examinedstructure parameters include negative junction depth, concave corner and effective channel length.Simulation results show that grooved gate device can suppress hot carrier effect deeply even indeep sub-micron region. The studies also indicate that hot carrier effect is strongly influencedby the concave corner and channel length for grooved gate device. With the increase of concavecorner, the hot carrier effect in grooved gate MOSFET decreases sharply, and with the reducingof effective channel length, the hot carrier effect becomes large.

Effective Channel Length Degradation under Hot-Carrier Stressing

This article describes the effective channel length degradation under hot carrier stressing. The extraction is based on the IDs-Vcs characteristics by maximum transconductance （maximum slope of IDs ＆ VGS） in the linear region. The transconductance characteristics are determine for the several devices of difference drawn channel length. The effective channel length of submicron LDD （Lightly Doped Drain） NMOSFETs （Metal Oxide Semiconductor Field Effect Transistor） under hot carrier stressing was measured at the stress time varying from zero to 10,000 seconds. It is shown that the effective channel length was increased with time. This is caused by charges trapping in the oxide during stress. The increased of effective channel length （△Leff） is seem to be increased sharply as the gate channel length is decrease.

“Hot Nano Spots” as an Interpretation of So-Called Non-Thermal Biological Mobile Phone Effects

Indications exist that mobile phones may cause non-specific biological effects. They are classified as being of implausible non-thermal nature due to low quantum energy and low specific absorption rate levels, even if considering worst cases of "hot spots" of only millimeter size. The considerations of this paper demonstrate that classical theory of polarization offers a conventional interpretation for all three the existence of so far unclarified effects, their low reproducibility and their low intensity. The basis of this explanation is given by the assumption that hot spots contain even hotter “nano spots” on a molecular level according to well known mechanisms of γ-relaxation. In this paper, the concept is put for discussion assuming a heterogeneous system that consists of water molecules as well as larger-sized functional molecules. A consistent interpretation through temperature increase on the level of nanometer sized molecular compounds promises to favor interdisciplinary discussions with respect to safety regulations.

Pressure Effects on the Charge Carrier Transportation of BaF_2 Nanocrystals

The charge transport behavior of barium fluoride nanocrystals is investigated by in situ impedance measurement up to 35 GPa. It is found that the parameters change discontinuously at about 6.9 GPa, corresponding to the phase transition of BaF2 nanocrystals under high pressure. The charge carriers in BaF2 nanocrystals include both Fions and electrons. Pressure makes the electronic transport more difficult. The defects at grains dominate the electronic transport process. Pressure could make the charge-discharge processes in the Fm3m phase more difficult.

New Forward Gated-Diode Technique for Separating Front Gate Interface- from Oxide-Traps Induced by Hot-Carrier-Stress in SOI-NMOSFETs

The front gate interface and oxide traps induced by hot carrier stress in SOI NMOSFETs are studied.Based on a new forward gated diode technique,the R G current originating from the front interface traps is measured,and then the densities of the interface and oxide traps are separated independently.The experimental results show that the hot carrier stress of front channel not only results in the strong generation of the front interface traps,but also in the significant oxide traps.These two kinds of traps have similar characteristic in increasing with the hot carrier stress time.This analysis allows one to obtain a clear physical picture of the effects of the hot carrier stress on the generating of interface and oxide traps,which help to understand the degradation and reliability of the SOI MOSFETs.

Unified Degradation Model in Low Gate Voltage Range During Hot-Carrier Stressing of p-MOS Transistors

Hot carrier effects of p MOSFETs with different oxide thicknesses are studied in low gate voltage range.All electrical parameters follow a power law relationship with stress time,but degradation slope is dependent on gate voltage.For the devices with thicker oxides,saturated drain current degradation has a close relationship with the product of gate current and electron fluence.For small dimensional devices,saturated drain current degradation has a close relationship with the electron fluence.This degradation model is valid for p MOSFETs with 0 25μm channel length and different gate oxide thicknesses.

1/f~γ Noise Characteristics of an n-MOSFET Under DC Hot Carrier Stress

The 1/fγ noise characteristic parameter Sfγ model in an n-MOSFET under DC hot carrier stress is studied. A method characterizing the MOSFET abilities of an anti-hot carrier with noise parameter Sfγ is presented. The hot carrier degradation effect of n-MOSFET in high-,mid-,and low gate stresses and its 1/fγ noise feature are studied. Experimental results agree well with the developed model.

Experimental Evidence of Interface-Trap-Related SILC in Ultrathin (4nm- and 2.5nm-Thick) n-MOSFET and p-MOSFET Under Hot-Carrier Stress

Stress-induced leakage current (SILC) of ultrathin gate oxide is investigated by observing the generation of interface traps for n-MOSFET and p-MOSFET under hot-carrier stress.It is found experimentally that there is linear correlation between the generation of interface traps and SILC for both types of MOSFET with different channel lengths (including 1,0.5,0.275,and 0.135μm) and different gate oxide thickness (4nm and 2.5nm).These experimental evidences show that the SILC has a strong dependence on interface traps.

An Improved Method to Extract Generation of Interface Trap in Hot-Carrier-Stressed LDD n-MOSFET

A new improved technique,based on the direct current current voltage and charge pumping methods,is proposed for measurements of interface traps density in the channel and the drain region for LDD n MOSFET.This technique can be applied to virgin samples and those subjected to hot carrier stress,and the latter are known to cause the interface damage in the drain region and the channel region.The generation of interface traps density in the channel region and in the drain region can be clearly distinguished by using this technique.

Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC): Occlusive Effect and Penetration Enhancement Ability

Objective: This work compares the occlusive effect and the penetration enhancement ability of solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), through in vitro skin. Methods: SLN and NLC were prepared by high shear homogenization and characterized by size, polydispersity index, zeta potential, morphology and physical stability. Occlusive effect was assessed by an in vitro test and by measuring TEWL using pig skin. Skin treated with the lipid carriers was visualized by SEM. A penetration test through skin, followed by tape stripping, was carried out using Nile red as a marker. Results: SLN (200 ± 6 nm) and NLC (192 ± 11 nm) were obtained. An occlusion factor of 36% - 39% was observed for both systems, while a reduction in TEWL of 34.3% ± 14.8% and 26.2% ± 6.5% was seen after treatment with SLN and NLC, respectively. SEM images showed a film formed by the lipid carriers, responsible for the occlusion observed. No differences were found between the occlusive effect produced by SLN and NLC in both tests. NLC allowed the penetration of a greater amount of Nile red than SLN: 4.7 ± 1.3 μg and 1.7 ± 0.4 μg, respectively. Conclusion: Both carriers form a film on the skin, providing an occlusive effect with no differences between these two systems. The penetration of a marker (Nile red) into the stratum corneum was quite higher for NLC than for SLN, suggesting an influence of the composition of these particles on their penetration enhancing ability.

Two-Dimensional Transition Metal Dichalcogenides and Their Charge Carrier Mobilities in Field-Effect Transistors

Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero band gap has limited its applications in electronic devices. Transition metal dichalcogenide(TMDC), another kind of 2D material,has a nonzero direct band gap(same charge carrier momentum in valence and conduction band) at monolayer state,promising for the efficient switching devices(e.g., field-effect transistors). This review mainly focuses on the recent advances in charge carrier mobility and the challenges to achieve high mobility in the electronic devices based on 2DTMDC materials and also includes an introduction of 2D materials along with the synthesis techniques. Finally, this review describes the possible methodology and future prospective to enhance the charge carrier mobility for electronic devices.