MOS Capacitance–Voltage Characteristics: IV. Trapping Capacitance from 3-Charge-State Impurities

Metal-Oxide-Semiconductor Capacitance-Voltage (MOSCV) characteristics containing giant carrier trapping capacitances from 3-charge-state or 2-energy-level impurities are presented for not-doped, n-doped, p-doped and compensated silicon containing the double-donor sulfur and iron, the double-acceptor zinc, and the amphoteric or one-donor and one-acceptor gold and silver impurities. These impurities provide giant trapping capacitances at trapping energies from 200 to 800 meV (50 to 200 THz and 6 to 1.5 μm), which suggest potential sub-millimeter, far-infrared and spin electronics applications.     

MOS Capacitance-Voltage Characteristics:V.Methods to Enhance the Trapping Capacitance

正Low-frequency and High-frequency Capacitance-Voltage(C-V) curves of Silicon Metal-Oxide-Semiconductor Capacitors,showing electron and hole trapping at shallow-level dopant and deep-level generation-recombination -trapping impurities,are presented to illustrate the enhancement of the giant trapping capacitances by physical means via device and circuit designs,in contrast to chemical means via impurity characteristics previously reported.Enhancement is realized by masking the electron or/and hole storage capacitances to make the trapping capacitances dominant at the terminals.Device and materials properties used in the computed CV curves are selected to illustrate experimental realizations for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.     

MOS Capacitance-Voltage Characteristics Ⅱ.Sensitivity of Electronic Trapping at Dopant Impurity from Parameter Variations

Low-frequency and high-frequency Capacitance-Voltage（C-V） curves of Metal-Oxide-Semiconductor Capacitors（MOSC）,including electron and hole trapping at the dopant donor and acceptor impurities,are presented to illustrate giant trapping capacitances,from>0.01C_ox to>10C_ox.Five device and materials parameters are varied for fundamental trapping parameter characterization,and electrical and optical signal processing applications.Parameters include spatially constant concentration of the dopant-donor-impurity electron trap,N_DD,the ground state electron trapping energy level depth measured from the conduction band edge, E_C—E_D,the degeneracy of the trapped electron at the ground state,g_D,the device temperature,T,and the gate oxide thickness,x_OX.     

MOS Capacitance-Voltage Characteristics Ⅲ.Trapping Capacitance from 2-Charge-State Impurities

Low-frequency and high-frequency capacitance-voltage curves of Metal-Oxide-Semiconductor Capacitors are presented to illustrate giant electron and hole trapping capacitances at many simultaneously present two-charge-state and one-trapped-carrier,or one-energy-level impurity species.Models described include a donor electron trap and an acceptor hole trap,both donors,both acceptors,both shallow energy levels,both deep,one shallow and one deep,and the identical donor and acceptor.Device and material parameters are selected to simulate chemically and physically realizable capacitors for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.     

MOS Capacitance–Voltage Characteristics from Electron-Trapping at Dopant Donor Impurity

The capacitance versus DC-voltage formula from electron trapping at dopant impurity centers is derived for MOS capacitors by the charge-storage method. Fermi–Dirac distribution and impurity deionization are included in the DC-voltage scale. The low-frequency and high-frequency capacitances, and their differences and derivatives, are computed in the presence of an unlimited source of minority and majority carriers. The results show that their difference and their DC-voltage derivatives, are large and readily measurable, hence suitable as a method for characterizing the electronic trapping parameters at dopant impurity centers and for a number of lower power signal processing and device technology monitoring applications.     

MOS Capacitance-Voltage Characteristics from Electron-Trapping at Dopant Donor Impurity

The capacitance versus DC-voltage formula from electron trapping at dopant impurity centers is derived for MOS capacitors by the charge-storage method.Fermi-Dirac distribution and impurity deionization are included in the DC-voltage scale.The low-frequency and high-frequency capacitances,and their differences and derivatives,are computed in the presence of an unlimited source of minority and majority carriers.The results show that their difference and their DC-voltage derivatives,are large and readily measurable,hence suitable as a method for characterizing the electronic trapping parameters at dopant impurity centers and for a number of lower power signal processing and device technology monitoring applications.     

Modeling of cylindrical surrounding gate MOSFETs including the fringing field effects

A physically based analytical model for surface potential and threshold voltage including the fringing gate capacitances in cylindrical surround gate(CSG) MOSFETs has been developed.Based on this a subthreshold drain current model has also been derived.This model first computes the charge induced in the drain/source region due to the fringing capacitances and considers an effective charge distribution in the cylindrically extended source/drain region for the development of a simple and compact model.The fringing gate capacitances taken into account are outer fringe capacitance,inner fringe capacitance,overlap capacitance,and sidewall capacitance.The model has been verified with the data extracted from 3D TCAD simulations of CSG MOSFETs and was found to be working satisfactorily.     

Optical trapping of metallic Rayleigh particle by combined beam

Radiation forces and trapping stability of metallic(i.e.gold) Rayleigh particle by combined beam are analyzed,and the combined beam is formed by superimposing two partially coherent off-axis flat-topped beams.The dependences of radiation forces on off-axis distance parameter,correlation length and particle radius are illustrated by numerical examples.The results show that there exist critical values d0,cand σ0,c for the combined beam.For 0相似文献   

NOVEL REALIZATION OF UNIT ELEMENT WAVE SWITCHED CAPACITOR FILTER

In this paper,some novel SC-adaptor circuits are presented to realize the unit element waveswitched capacitor filter using two-phase clock signals.These circuits are insensitive to the bottomplate parasitic capacitances and request only one unit-gain buffer to realize an adaptor.The effectsof top plate parasitic capacitances and switch parasitic capacitances on an adaptor are analyzed.The results show that the effects of those are small and can be reduced further by adjusting onlyone of the capacitances.These circuits are adaptable for realizing programmable filters and veryuseful to the LPC real-time speech synthesis.As an example,a 5th order unit element low-passfilter is given.The experimental results are in excellent agreement with the theory.     

Time of flight experimental studies of CdZnTe radiation detectors

A time of flight technique was used to study the carrier trapping time, τ, and mobility, μ, in CdZnTe (CZT) and CdTe radiation detectors. Carriers were generated near the surface of the detector by a nitrogen-pumped pulsed dye laser with wavelength ∼500 nm. Signals from generated electrons or holes were measured by a fast oscilloscope and analyzed to determine the trapping time and mobility of carriers. Electron mobility was observed to change with temperature from 1200 cm²/Vs to 2400 cm²/Vs between 293 K and 138 K, respectively. Electron mobilities were observed between 900 cm²/Vs and 1350 cm²/Vs at room temperature for various CZT detectors. Electron mobilities in various CdTe detectors at room temperature were observed between 740 cm²/Vs and 1260 cm²/Vs. Average electron mobility was calculated to be 1120 cm²/Vs and 945 cm²/Vs for CZT and CdTe, respectively. Hole mobilities in both CZT and CdTe were found to vary between 27 cm²/Vs and 66 cm²/Vs. Electron trapping times in CZT at room temperature varied from 1.60 μs to 4.18 μs with an average value of about 2.5 μs. Electron trapping time in CdTe at room temperature varied between 1.7 μs and 4.15 μs with an average value of about 3.1 μs.     

三栅 SuperFlash闪存的耐久性退化机理特性

Write/erase degradation after endurance cycling due to electron trapping events in triple-gate flash memory have been detected and analyzed using a UV erasure method. Different from the commonly degradation phenomenon, write-induced electron trapping in the floating gate oxide, electron trapping in tunneling oxide is observed in triple-gate flash memory. Further, the degradation due to single-electron locally trapping/de-trapping in hornshaped SuperFlash does not occur in the triple-gate flash cell This is because of planar poly-to-poly erasing in the triple-gate flash cell instead of tip erasing in the horn-shaped SuperFlash cell Moreover, by TCAD simulation, the trap location is identified and the magnitude of its density is quantified roughly.     

Thermally conducting polymer-matrix composites containing both AIN particles and SiC whiskers

Aluminum nitride particles (size 4 [μa.) and silicon carbide whiskers (diameter 1.4 (μm, length 18.6 μm) were used as fillers in a polyimide polymer matrix. Aluminum nitride in the amount of 50 vol.% decreased the coefficient of thermal expansion from 81 x 10^-6 to 11.3 x lO^-6/dgC and increased the thermal conductivity from 0.128 up to 1.76 W/(m.°C). Silicon carbide in the amount of 50 vol.% decreased the coefficient of thermal expansion from 81 x 10^-6 to 18.1 x 10^-6°C and increased the thermal conductivity from 0.128 up to 1.26 W/(m.°C). When both SiC whiskers and A1N particles in the 1:3 volume ratio and in the total amount of 50 vol.% were added to the polymer, the thermal conductivity increased from 0.128 to 2.23 W/(m.°C). These effects are attributed to the large aspect ratio of the SiC whiskers, which tended to bridge adjacent A1N particles and also act as a reinforcement to improve the toughness of the composite. On the other hand, the SiC whiskers in the mixed fillers also enhanced the toughness of the composites. The composite containing 50 vol.% A1N particles alone had a lower dielectric constant (7.1 at 100 kHz) than the composite containing 50 vol.% SiC whiskers alone (15.9 at 100 kHz). The composites containing a mixture of A1N particles and SiC whiskers at different ratios and in the total amount of 50 vol.% had lower values of the dielectric constant than the composite containing SiC whiskers alone.     

一种新型的带栅形条电容和可变间距电容的惯性信号检测结构

The comb capacitances fabricated by deep reactive ion etching （RIE） process have high aspect ratio which is usually smaller than 30 ： 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate＇s effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio （30 ： 1） of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy （FEM） tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.     

High Power,Room Temperature Terahertz Emitters Based on Dopant Transitions in 6H-Silicon Carbide

Electrically pumped high power terahertz(THz) emitters that operated above room temperature in a pulse mode were fabricated from nitrogen-doped n-type 6H-SiC. The emission spectra had peaks centered on 5 THz and 12 THz(20 meV and 50 meV) that were attributed to radiative transitions of excitons bound to nitrogen donor impurities. Due to the relatively deep binding energies of the nitrogen donors, above 100 meV, and the high thermal conductivity of the SiC substrates, the THz output power and operating temperature were significantly higher than previous dopant based emitters.With peak applied currents of a few amperes, and a top surface area of 1 mm2, the device emitted up to 0.5 mW at liquid nitrogen temperature(77 K), and tens of microwatts up to 333 K. This result is the highest temperature of THz emission reported from impuritybased emitters.     

The effect of microstructural and geometrical features on the reliability of ultrafine flip chip microsolder joints

A thermodynamic approach was used to investigate solder alloy systems containing Sn, Ag, Sb, and Pb, during both equilibrium and Scheil cooling conditions. The modeled microstructure was used to explore recent experimental results and to establish the microstructure-property relationships in microsolder joints. This approach is shown to be very useful in the transition from Pb-Sn to lead-free solders by enabling the consideration of contamination by a small amount of Pb. Molten solder interacts with the under bump metallization or print circuit board (PCB) metallization to form intermetallic compounds (IMCs). A truncated sphere structure was used to predict the solder joint geometry, and a two-dimensional finite-element (FE) method was adopted to investigate the kinetics of the dissolution of Au during the reflow process. The dissolution of Au into different volumes of solder material for three sizes of joints has been studied. In the modeling of the dissolution kinetics, the Nernst-Brunner equation is found to have poor validity for these calculations because of the dramatic change in the microscopic geometry and boundary conditions for joints at 100 μm in size or smaller. A combined thermodynamic and kinetic modeling approach, with a novel interface for implementation, is also briefly discussed.     

Ammonothermal synthesis of aluminum nitride crystals on group III-nitride templates

Polycrystalline aluminum nitride (AlN) crystals were synthesized using the ammonothermal technique at temperatures between 525°C and 550°C. The growth of AlN was conducted in alkaline conditions with potassium azide (KN₃) as the mineralizer. The growth mechanism was found to be reversegradient soluble, necessitating the placement of the GaN and AlN seeds at a higher temperature than the aluminum metal source. Growth on the GaN seeds varied from 100 to 1500 μm in thickness at a gestation period of 21 days. Additionally, scanning electron micrographs revealed varying microstructure ranging from pointed hexagonal rods, which are approximately 5 μm wide and 20 μm long, to highly densified and contiguous films. Formation of hexagonal AlN was verified using x-ray powder diffraction measurements. Oxygen was detected at 3.7 at.% by inert gas fusion analysis on AlN nucleated on the walls of the autoclave and a qualitative indication of unintentionally incorporated impurities in the AlN grown on the GaN seeds was obtained using energy-dispersive x-ray analysis. Photoluminescence spectroscopy conducted at 20 K revealed a deep-level emission at 3.755 eV due to unintentionally incorporated impurities.     

Strain tunable quantum dot based non-classical photon sources

Semiconductor quantum dots are leading candidates for the on-demand generation of single photons and entangled photon pairs.High photon quality and indistinguishability of photons from different sources are critical for quantum information applications.The inability to grow perfectly identical quantum dots with ideal optical properties necessitates the application of post-growth tuning techniques via e.g.temperature,electric,magnetic or strain fields.In this review,we summarize the state-of-the-art and highlight the advantages of strain tunable non-classical photon sources based on epitaxial quantum dots.Using piezoelectric crystals like PMN-PT,the wavelength of single photons and entangled photon pairs emitted by InGaAs/GaAs quantum dots can be tuned reversibly.Combining with quantum light-emitting diodes simultaneously allows for electrical triggering and the tuning of wavelength or exciton fine structure.Emission from light hole exciton can be tuned,and quantum dot containing nanostructure such as nanowires have been piezo-integrated.To ensure the indistinguishability of photons from distant emitters,the wavelength drift caused by piezo creep can be compensated by frequency feedback,which is verified by two-photon interference with photons from two stabilized sources.Therefore,strain tuning proves to be a flexible and reliable tool for the development of scalable quantum dots-based non-classical photon sources.     

高K栅堆叠结构MOSFET器件阈值电压不稳定度的半经验解析模型

A semi-empirical analytic model for the threshold voltage instability of MOSFET is derived from the Shockley-Read-Hall (SRH) statistics in this paper to account for the transient charging effects in a MOSFET high-k gate stack. Starting from the single energy level and single trap assumption, an analytical expression of the filled trap density in terms of the dynamic time is derived from the SRH statistics. The semi-empirical analytic model of the threshold voltage instability is developed based on the MOSFET device physics between the threshold voltage and the induced trap density. The obtained model is also verified by the extensive experimental data of the trapping and de-trapping stress from the different high k gate configuration.     

Quantum and Transport Mobilities of a Two-Dimensional Electron Gas in the Presence of the Rashba Spin-Orbit Interaction

A systematic theoretical approach is developed to study the electronic and transport properties of a twodimensional electron gas (2DEG) in the presence of spin-orbit interactions induced by the Rashba effect. The standard random-phase approximation is employed to calculate the screening length caused by electron-electron interaction in different transition channels. The quantum and transport mobilities in different spin branches are evaluated using the momentum-balance equation derived from the Boltzmann equation,in which the electron interactions with both the remote and background impurities are taken into account in an InAlAs/InGaAs heterojunction at low-temperatures.     

A millimeter wave large-signal model of GaAs planar Schottky varactor diodes

A millimeter wave large-signal model of GaAs planar Schottky varactor diodes based on a physical analysis is presented.The model consists of nonlinear resistances and capacitances of the junction region and external parasitic parameters.By analyzing the characteristics of the diode under reverse and forward bias,an extraction procedure of all of the parameters is addressed.To validate the newly proposed model,the PSVDs were fabricated based on a planar process and were measured using an automatic network analyzer.Measurement shows that the model exactly represents the behavior of GaAs PSVDs under a wide bias condition from -10 to 0.6 V and for frequencies up to 40 GHz.