Some results on the molecular-beam epitaxial growth of HgCdTe focusing on the requirements of the 3rd generation infrared focal plane arrays are described.Good uniformity is observed over 75mm HgCdTe epilayers,and the deviation in cutoff wavelength is within 0.1μm at 80K.A variety of surface defects are observed and the formation mechanism is discussed.The average density of surface defects in 75mm HgCdTe epilayers is found to be less than 300cm-2.It is found that the surface sticking coefficient of As during HgCdTe growth is very low and is sensitive to growth temperature,being only ～1E-4 at 170℃.The activation energy of As in HgCdTe was determined to be 19.5meV,which decreases as (Na-Nd)1/3 with a slope of 3.1E-5meV·cm.The diffusion coefficients of As in HgCdTe of 1.0±0.9E-16,8±3E-15,and 1.5±0.9E-13cm2/s are obtained at temperatures of 240,380,and 440℃,respectively under Hg-saturated pressure.The MBE-grown HgCdTe is incorporated into FPA fabrications,and the preliminary results are presented.

The continued development of CMOS technology and the emergence of new applications demand continued improvement and enhancement of compact models.This paper outlines the recent work of the BSIM project at the University of California,Berkeley,including BSIM5 research,BSIM4 enhancements,and BSIMSOI development.BSIM5 addresses the needs of nano-CMOS technology and RF high-speed CMOS circuit simulation.BSIM4 is a mature industrial standard MOSFET model with several improvements to meet the technology requirements.BSIMSOI is developed into a generic model framework for PD and FD SOI technology.An operation mode choice,via the calculation of the body potential ΔVbi and body current/charge,helps circuit designers in the trend of the coexistence of PD and FD devices.

The transitions of E0,E0+Δ0, and E+ in dilute GaAs1-xNx alloys with x=0.10%,0.22%,0.36%,and 0.62% are observed by micro-photoluminescence.Resonant Raman scattering results further confirm that they are from the intrinsic emissions in the studied dilute GaAsN alloys rather than some localized exciton emissions in the GaAsN alloys.The results show that the nitrogen-induced E+ and E0+Δ0 transitions in GaAsN alloys intersect at a nitrogen content of about 0.16%.It is demonstrated that a small amount of isoelectronic doping combined with micro-photoluminescence allows direct observation of above band gap transitions that are not usually accessible in photoluminescence.

The influence of polarization-induced electric fields on the electron distribution and the optical properties of intersubband transitions (ISBT) in AlxGa1-xN/GaN coupled double quantum wells (DQWs) is investigated by self-consistent calculation.It is found that the polarization-induced potential drop leads to an asymmetric potential profile of AlxGa1-xN/GaN DQWs even though the two wells have the same width and depth.The polarization effects result in a very large Stark shift between the odd and even order subbands,thus shortening the wavelength of the ISBT between the first odd order and the second even order (1odd-2even) subbands.Meanwhile,the electron distribution becomes asymmetric due to the polarization effects,and the absorption coefficient of the 1odd-2even ISBT decreases with increasing polarization field discontinuity.

The effects of the transition metals copper and nickel on oxygen precipitation in Czochralski silicon under a rapid thermal process are investigated.It is found that interstitial copper has almost no effect on oxygen precipitation,but copper precipitation markedly enhances oxygen precipitation.However,neither interstitial nickel nor nickel precipitation affects oxygen precipitation.The reasons for the effects of copper and nickel contamination on oxygen precipitation are discussed in light of oxygen precipitation nucleation theory.

High quality GaN is grown on GaN substrate with stripe pattern by metalorganic chemical vapor deposition by means of epitaxial lateral overgrowth.AFM,wet chemical etching,and TEM experiments show that with a two-step ELOG procedure,the propagation of defects under the mask is blocked,and the coherently grown GaN above the window also experiences a drastic reduction in defect density.In addition,a grain boundary is formed at the coalescence boundary of neighboring growth fronts.The extremely low density of threading dislocations within wing regions makes ELOG GaN a potential template for the fabrication of nitride-based lasers with improved performance.

Using a nanoscale silica fiber taper,light can be efficiently coupled into a single ZnO nanowire by means of evanescent coupling.The method is valid for launching light into a single nanowire in the ultraviolet to infrared range with a coupling efficiency of 25%.Low-loss optical guiding of ZnO nanowires is demonstrated,and the photoluminescence of a single ZnO nanowire is also observed.Compared to conventional approaches in which a lens-focused laser beam is used to excite nanowires at specific wavelengths,this evanescent coupling approach has advantages such as high coupling efficiency and broad-band validity,and it is promising for the optical characterization of semiconductor nanowires or nanoribbons.

A novel double-layer film of SiCOF/a-C∶F with a low dielectric constant is deposited using a PECVD system.The chemical structure of the film is characterized with Fourier transform infrared spectroscopy (FTIR).The measurements of the film refractive index reveal that the optical frequency dielectric constant (n2) of the film is almost constant as a function of air exposure time,however,with increasing annealing temperature,the value of n2 for the film decreases.Possible mechanisms are discussed in detail.The analysis of SIMS profiles for the metal-insulator-silicon structures reveal that in the Al/a-C∶F/Si structure,the annealing causes a more rapid diffusion of F in Al in comparison with C,but there is no obvious difference in Si.In addition,no recognizable verge exists between SiCOF and a-C∶F films,and the SiCOF film acts as a barrier against the diffusion of carbon into the aluminum layer.

self-aligned InP/GaInAs single heterojunction bipolar transistor(HBT) is investigated using a novel T-shaped emitter.A U-shaped emitter layout,selective wet etching,laterally etched undercut,and an air-bridge are applied in this process.The device,which has a 2μm×12μm U-shaped emitter area,demonstrates a common-emitter DC current gain of 170,an offset voltage of 0.2V,a knee voltage of 0.5V,and an open-base breakdown voltage of over 2V.The HBT exhibits good microwave performance with a current gain cutoff frequency of 85GHz and a maximum oscillation frequency of 72GHz.These results indicate that these InP/InGaAs SHBTs are suitable for low-voltage,low-power,and high-frequency applications.

For the treatment of the quantum effect of charge distribution in nanoscale MOSFETs,a quantum correction model using Levenberg-Marquardt back-propagation neural networks is presented that can predict the quantum density from the classical density.The training speed and accuracy of neural networks with different hidden layers and numbers of neurons are studied.We conclude that high training speed and accuracy can be obtained using neural networks with two hidden layers,but the number of neurons in the hidden layers does not have a noticeable effect.For single and double-gate nanoscale MOSFETs,our model can easily predict the quantum charge density in the silicon layer,and it agrees closely with the Schrodinger-Poisson approach.

This paper presents a novel scheme for enhancing resistance that utilizes an equivalent negative resistance.Adopting this novel scheme in the proposed current source could remarkably boost its output resistance without requiring increased power supply.Simulation with 0.6μm CMOS process models shows that the output resistance of the novel current source can reach the order of 1E9Ω with a 1.04GHz bandwidth and only 10.6ppm/℃ in the range of -40～145℃.

By complementing the equivalent oxide thickness (EOT) of a 1.7nm nitride/oxynitride (N/O) stack gate dielectric (EOT=1.7nm) with a W/TiN metal gate electrode,metal gate CMOS devices with sub-100nm gate length are fabricated in China for the first time.The key technologies adopted to restrain SCE and to improve drive ability include a 1.7nm N/O stack gate dielectric,non-CMP planarization technology,a T-type refractory W/TiN metal stack gate electrode,and a novel super steep retrograde channel doping using heavy ion implantation and a double sidewall scheme.Using these optimized key technologies,high performance 95nm metal gate CMOS devices with excellent SCE and good driving ability are fabricated.Under power supply voltages of VDS＝±1.5V and VGS=±1.8V,drive currents of 679μA/μm for nMOS and -327μA/μm for pMOS are obtained.A subthreshold slope of 84.46mV/dec,DIBL of 34.76mV/V,and Vth of 0.26V for nMOS,and a subthreshold slope of 107.4mV/dec,DIBL of 54.46mV/V,and Vth of –0.27V for pMOS are achieved.These results show that the combined technology has indeed thoroughly eliminated the boron penetration phenomenon and polysilicon depletion effect,effectively reduced gate tunneling leakage,and improved device reliability.

A novel flash memory cell with stacked structure (Si substrate/SiGe quantum dots/tunneling oxide/poly-Si floating gate) is proposed and demonstrated to achieve enhanced F-N tunneling for both programming and erasing.Simulation results indicate the new structure provides high speed and reliability.Experimental results show that the operation voltage can be as much as 4V less than that of conventional full F-N tunneling NAND memory cells.Memory cells with the proposed structure can achieve higher speed,lower voltage,and higher reliability.

A monolithic LC-tuned voltage controlled oscillator (LC-VCO) with 2 tuning terminals is designed for a dual frequency conversion transceiver for WLAN and realized using 0.18μm radio frequency (RF) CMOS technology.The output frequency range can be tuned to cover the defined frequency band of the transceiver.The maximum tuning range is 500MHz.The phase noises are -117dBc/Hz at 4MHz and -107dBc/Hz at 500kHz,both off the center frequency of 4.189GHz.The RMS-jitter of the output signal is 4.423ps,and the output power is –8.68dBm.

A 1.9GHz down-conversion CMOS mixer with a novel folded Gilbert cell,intended for use in GSM1900(PCS1900) low-IF receivers,is fabricated in a RF 0.18μm CMOS process.The prototype demonstrates good performance at an intermediate frequency of 100kHz.It achieves a conversion gain of 6dB,SSB noise figure of 18.5dB (1MHz IF),and IIP3 11.5dBm while consuming a 7mA current from a 3.3V power supply.

A differential equation for calculating squeeze-film air damping in slotted plates is developed by modifying the Reynolds equation.A term is added to account for the effect of airflow through the slots on the air damping of the plate.The end effect of the airflow in the slots is also treated by substituting an effective channel length for the geometric channel length (i.e.the thickness of the plate).The damping pressure distribution,damping force,and damping force coefficient of the slotted plates can be found by solving the equation under appropriate boundary conditions.With restrictions on the thickness and the lateral dimensions of the slotted plate removed,the equation provides a useful tool for analysing the squeeze-film air damping effect of slotted plates with finite thickness and finite lateral dimensions.For a typical slotted plate structure,the damping force coefficient obtained by this equation agrees well with that generated by ANSYS.

A micro direct methanol fuel cell (μDMFC) using MEMS technology is reported.The prototype features a unique 3D air-breathing cathode structure fabricated using KOH etching and double-side lithography.The optimization of the MEMS fabrication process is analyzed.The experimental results show the prototype generates a maximum power density of 2.52mW/cm2 at room temperature.This performance is better than the published results of other silicon-based passive μDMFCs.Moreover,it is comparable with that of our previous active μDMFCs which require an external pump,certificating the feasibility of this new configuration.

The growth of multi-layer InGaAs/InAs/GaAs self-assembled quantum dots (QDs) by molecular beam epitaxy (MBE) is investigated,and a QD laser diode lasing at 1.33μm in continuous operation mode at room temperature is reported.The full width at half maximum of the band edge emitting peaks of the photoluminescence (PL) spectra at room temperature is less than 35meV for most of the multi-layer QD samples,revealing good,reproducible MBE growth conditions.Moreover,atomic force microscopy images show that the QD surface density can be controlled in the range from 1E10 to 7E10cm-2.The best PL properties are obtained at a QD surface density of about 4E10cm-2.Edge emitting lasers containing 3 and 5 stacked QD layers as the active layer lasing at room temperature in continuous wave operation mode are reported.

The quantum dynamics of an exciton dressed by acoustic phonons in an optically driven quantum dot-semiconductor microcavity at finite temperatures is investigated theoretically by quantum optics methods. It is shown that the temperature dependence of the vacuum Rabi splitting is 22g×exp［-∑qλq(Nq+1/2)］,where Nq=1/［exp(ωq/kBT)-1］ is the phonon population, g is the single-photon Rabi frequency, and λq corresponds to exciton-phonon coupling.

A silicon-based photonic switch is proposed and simulated based on the multimode interference (MMI) principle and the free-carrier plasma dispersion effect in silicon-germanium.The proposed switch,designed for 1.55μm window operation,is useful for DWDM optical networks.The switch consists of two input single-mode ridge waveguide ports,a MMI section,and three output single-mode ridge waveguide ports.In the MMI section,two index-modulation regions are placed to divert input optical signals from the two input ports to each of the three output ports.Switching characteristics are demonstrated theoretically by a beam propagation method for 1.55μm operation.The simulated results show that the insertion loss of the switch is less than 1.43dB,and the crosstalk is between -18 and –32.8dB.

Time-dependent thermal simulation of ridge-geometry InGaN laser diodes is carried out with a two-dimensional model.A high temperature in the waveguide layer and a large temperature step between the regions under and outside the ridge are generated due to the poor thermal conductivity of the sapphire substrate and the large threshold current and voltage.The temperature step is thought to have a strong influence on the characteristics of the laser diodes.Time-resolved measurements of light-current curves,spectra,and the far-field pattern of the InGaN laser diodes under pulsed operation are performed.The results show that the thermal lensing effect improves the confinement of the higher order modes and leads to a lower threshold current and a higher slope efficiency of the device while the high temperature in the active layer results in a drastic decrease in the slope efficiency.

We present an improved angle polishing method in which the end of the cover slice near the glue layer is beveled into a thin,defect-free wedge,the straight edge of which is used as the datum for measuring the depth of subsurface damage.The bevel angle can be calculated from the interference fringes formed in the wedge.The minimum depth of the subsurface damage that can be measured by this method is a few hundred nanometers.Our results show that the method is straightforward,accurate,and convenient.

An equivalent circuit for a novel RF integrated inductor with ferrite thin-film is derived.The enhancement of the magnetic ferrite thin-film on the inductance (L) and quality factor (Q) of the inductor is analyzed.Circuit element parameters are extracted from RF measurements.Compared with the reference air-core inductor without magnetic film,L and Q of the ferrite thin-film inductor are 17% and 40% higher at 2GHz,respectively.Both the equivalent circuit analysis and test results demonstrate significant enhancement of the performance of RF integration inductors by ferrite thin-film integration.

The effects of adjacent metal layers and space between metal lines on the temperature rise of multilevel ULSI interconnect lines are investigated by modeling a three-layer interconnect.The heat dissipation of various metallization technologies concerning the metal and low-k dielectric employment is simulated in detail.The Joule heat generated in the interconnect is transferred mainly through the metal lines in each metal layer and through the path with the smallest thermal resistance in each Ield layer.The temperature rises of Al metallization are approximately ρAl／ρCu times higher than those of Cu metallization under the same conditions.In addition,a thermal problem in 0.13μm globe interconnects is studied for the worst case,in which there are no metal lines in the lower interconnect layers.Several types of dummy metal heat sinks are investigated and compared with regard to thermal efficiency,influence on parasitic capacitance,and optimal application by combined thermal and electrical simulation.

By combining the measurement results of electrical properties and deep level defects,the electrical properties,thermal stability,and electrical uniformity of semi-insulating single crystal InP are demonstrated that they have a close correlation with the content of the deep level defects.An approach to improving the material quality is given through analysis of the dependence of the deep level defects on annealing and growth conditions.The formation mechanism and nature of the deep level defects are discussed.

Electric parameters including resistivity,mobility,and free carrier concentration are measured at low temperatures for n-type 6H-SiC from China and Cree corporation.Their impurity concentration and levels are obtained from the fitting data of FCCS.The experimental results show that the concentration and compensation level of the impurity greatly affect the electric properties of SiC at low temperatures.The two different levels of nitrogen donor work together for 6H-SiC with a low compensation,but the accepter levels work at low temperatures for 6H-SiC with a high compensation.The peak of the mobility curve of the latter decreases and moves to the right as temperature increases.At the same time,the highly compensated SiC is transformed from n-type to p-type at low temperatures,which is analyzed theoretically.

In2O3 nanowires are fabricated successfully with a high temperature tube furnace.SEM photos show the formation of the nanowires.XRD analyses indicate that the In2O3 nanowires are cubic crystals.XPS analyses indicate that there are many oxygen defects in the In2O3 nanowires.The In2O3 nanowires can emit very bright ultraviolet light at 396nm,which is detected by PL.The emission and reaction mechanisms are discussed in detail at last.

AlSb thin films are prepared using two-stage processes.Al and Sb are deposited onto a glass substrate by magnetron sputtering to produce Al/Sb prefabricated films.The prefabricated films become polycrystalline after being annealed at 560℃ in argon atmosphere.Different film structures and compositions are characterized by X-ray diffraction and scanning electron microscopy.It is found that the polycrystalline AlSb films are uniformly packed with a grain size of about 20nm.Conductance activation energies of 0.21 and 0.321eV are obtained from the dark conductivity temperature curves.This will be useful for future fabrication of AlSb solar cells.

An effective preparation method is proposed for a type of organic/metal Schottky diode.An organic film,3,4∶9,10 perylenetetracarboxylic dianhydride (PTCDA) , and a metal electrode Au are deposited on the ITO respectively with a simple vacuum evaporation technology.The I-V properties of the diode,measured at room temperature,show that the commutating coefficient of the devices reaches 1E4.According to standard Schottky theory and the measurements of capacitance-frequency and capacitance-voltage,we can conclude that the organic Schottky potential is about 0.2～0.3eV.

By utilizing the linear relationship between the threshold voltage of a MOS transistor and its temperature,an improved built-in digital temperature sensor,which is based on a relaxation oscillator,is provided,and a novel built-in digital temperature sensor,which is based on the Schmitt trigger,is developed for thermal test and the protection of integrated circuits.The simulation results show that the accuracies of the two types of the sensors are both within 1℃Only 19 transistors are needed by the Schmitt trigger based temperature sensor,saving at least 26.9% of the number of transistors as compared with previous work.

36GHz voltage-controlled oscillator is designed and realized in OMMIC’s 0.2μm GaAs PHEMT technology.A fully differential structure is applied in the tunable oscillator.In order to improve the circuit performance,a capacitive-source-coupled current amplifier is used as the active part,and a single-tuned tank as a load.The measurement results show that the center frequency of the VCO is 36GHz and the tuning-range is 800MHz.The phase noise is –98.83dBc/Hz at a 10MHz offset.The chip area is 0.5mm×1mm,and the DC power consumption of the core is 200mW under a single -5V power supply.

Through the study of a failure mechanism model--the Arrhenius model--of electronic devices in accelerated testing,it is found that the relation between the rate of degradation of failure sensitive parameters and the negative reciprocal of operating stress follows an exponential rule in accelerated testing.Based on the relationship,a failure-mechanism identification method in accelerated testing is presented.Then a progress-stress accelerated test is constructed in the temperature range of 150～310℃,and the consistent failure-mechanism range proves that the method is feasible.