Temperature effects in silicon avalanche diodes

Gain-voltage curves for reach-through avalanche photodiodes are computed using the ionization rate data of van Overstraeten and de Man and Lee et al. and compared with measured curves. Noise spectral density measurements are also made and compared with McIntyre's avalanche noise theory. Agreement between computed and measured k-values as obtained from the noise measurements and between the computed and measured gain-voltage relationship can only be obtained with the ionization rate data of Lee et al. Gain-voltage curves were measured over the temperature range ?17 to +55°C and compared with computed curves in which temperature dependence of the ionization rate data of Lee et al. is computed using the modified Baraff theory. Excellent agreement between theory and experiment is obtained.     

The use of langmuir probe measurements to investigate the reaction mechanisms of remote plasma-enhanced chemical vapor deposition

Langmuir probe measurements of plasma density and electron temperature have been used to investigate the reaction kinetics in remote plasma-enhanced chemical vapor deposition (RPCVD) of Si on Si (100) substrates. The increased growth rate for negative substrate bias indicates that positively charged ions are involved in the deposition reaction. A comparison of growth rate and plasma density data indicates that the growth rate is proportional to the ion flux. It is concluded that the rate limiting reaction in RPCVD is H desorption from the hydrogenated Si surface by ion bombardment.     

Interface states in SiSiO2 interfaces

Interface state parameters were studied in MOS capacitors over a wide range of energy by conductance and capacitance measurements at various temperatures from room temperature to liquid nitrogen temperature. A new technique was developed for analysis of the data which allows to obtain the density of states, the capture cross section, the surface potential and the dispersion parameter from the conductance and capacitance vs. frequency curves. The density of interface states as well as the electron capture cross section were found to be a function of energy only and to be independent of temperature. Maxima in the density of states have not been found.     

A Numerical Method for Calibrating Microwave Cavities for Plasma Diagnostics---Part I

Computer programs are described which generate calibration curves for TE/sub 0np/ and TM/sub 0n0/ cylindrical microwave cavities used in plasma diagnostics. The programs provide data for electron densities well above those at which perturbation theory fails, and can be used for any specified variation of electron density with radius.     

Electron density and temperature measurements of the ignited mode plasma in a thermionic converter

Spectroscopic measurements of the electron density and temperature have been made on a planar thermionic converter operated in the quasi-saturation region of the ignited mode. The effects of several independent converter variables on the electron density were investigated quantitatively. From this investigation it was found that the emitter temperature and current density were the most significant parameters affecting the electron density. Collector temperature, cesium vapor pressure, and interelectrode spacing were less important. Complete electron density profiles and electron temperature profiles were obtained and compared to conditions characteristic of local thermodynamic equilibrium (LTE). A representative case indicated the measured temperature, 2600°K, was only 200°K higher than required for complete LTE in the region of the peak electron density. This corresponds to an electron density approximately 45 percent below the equilibrium value.     

A new AC technique for accurate determination of channel charge and mobility in very thin gate MOSFET's

A new method is described for determining the channel charge and mobility of a MOS transistor as a function of gate bias from the ac admittance measurements. The admittance of the conduction channel of the MOSFET is derived from a transmission line model. The peaks of theG/omegaversus ω curves are used to deduce gate-channel capacitance and mobility. The mobile carrier density and mobility in very thin-oxide MOSFET's can be measured more accurately using this ac method, since a zero lateral field and a uniform mobile charge distribution along the channel is maintained with zero drain-source voltage and interface trap effects are reduced by using high test frequencies. Measured data on the electron mobility versus gate voltage are presented for 90-A gate dielectric MOS transistors.     

样品温度对激光诱导黄铜等离子体辐射特性的影响

为了研究样品温度变化对激光诱导铜等离子体特征参数的影响,利用单脉冲激光诱导激发加热台上的样品形成等离子体, 改变样品温度获得相应的黄铜等离子体发射光谱。分析了样品温度变化时特征谱线强度的变化,并在局部热 平衡(Local thermodynamic equilibrium, LTE)条件下,利用Boltzman方程和Stark展宽计算并获得不同样品温度 条件下等离子体电子温度和电子密度随时间的演化规律,同时讨论了激光诱导金属等离子体光谱增强的原因。 实验结果表明,延迟时间相同时,样品温度越高,谱线强度越强,电子温度和电子密度越大。由此可见, 适当升高样品温度可以提高谱线强度。     

钨电极辅助微波等离子体水蒸汽制氢的多物理场计算

通过电磁场和等离子体场耦合的方法对钨电极辅助微波等离子体制氢过程进行多物理场耦合计算,并对制氢过程中的电子密度、电子温度、氢气和水蒸汽的浓度进行计算.计算结果表明,在10-16 s到10-15 s过程中,电子密度和电子温度增加并由电极向四周扩散,氢气浓度缓慢增加.在10-15S到10-14S过程中,电子密度和电子温度分...     

退火与未退火MM-HEMT材料中二维电子气的磁输运特性研究

采用变磁场霍耳测量,在1.5～90K的温度范围内,研究了经过快速热退火与未退火掺杂MM-HEMT材料中二维电子气的输运特性.通过对Shubnikov-de Hass(SdH)振荡曲线进行快速Fourier变换分析,获得了该样品沟道中子能带上的电子浓度等信息,并采用迁移率谱(MS)和多载流子拟合过程法(MFC)相结合的方法分析了该样品中子能带电子的浓度和迁移率.该方法与SdH测量所获得的结果符合得很好,都证实了在很高的温度下退火将影响样品沟道中电子的浓度和迁移率,对材料性能起着不可低估的作用.     

In-situ sem observation of electromigration in thin metal films at accelerated stress conditions

With so-called in-situ SEM experiments, electromigration experiments are performed in a SEM (scanning electron microscope) equipped with a heating stage. BSE (back scattered electron) images are taken continuously over the entire length of a metal line submitted to high current and temperature stress, monitoring in detail the microstructure. Comparing the electrical resistance curves with the corresponding SEM micrographs and with ex-situ AFM measurements leads to detailed qualitative and quantitative information about the occurring electromigration and precipitation / dissolution effects in the metal lines.     

LPE and VPE In1-xGaxAsyP1-y/InP: Transport properties, defects, and device considerations

The electrical properties of In1-xGaxAsyP1-yalloys lattice matched to InP, grown by liquid-phase and vapor-phase epitaxial techniques, have been determined by various measurements. Several electron and hole traps, with activation energies varying from 0.26 to 0.82 eV, have been identified by transient capacitance and photocapacitance measurements and their density and capture cross section have been measured. The 0.82 electron trap has emission and capture properties identical to the dominant 0.83 eV electron trap present in bulk and VPE GaAs. Hall measurements were made on the alloys in the temperature range of 20-600 K. Analysis of the mobility data has yielded the values of several transport parameters including the alloy scattering potentialDelta Uas a function of composition. The maximum value ofDelta U simeq 0.8eV corresponding to the bandgapE_{g} simeq 0.95eV. Photo-Hall measurements at low temperatures show the presence of donor- and acceptor-like defects in the LPE and VPE alloys, respectively. These centers exhibit persistent photoconductivity at low temperatures and have a high barrier energy (∼0.2 eV) associated with electron capture. Defects, which are possibly located in the interconduction-valley region, have been identified from analysis of Hall data forT > 400K. The strong temperature dependence of the threshold current in injection lasers and the large leakage currents near breakdown in avalanche photodiodes have been discussed in the fight of the defects identified in the present investigation.     

Time-resolved measurements of excited state densities in a coppervapor laser

Time-resolved measurements of copper and neon buffer gas excited-state densities in a copper vapor laser (CVL) during the excitation pulse and early afterglow are reported for both optimum and nonoptimum power-input conditions. The optimum condition results demonstrate that the termination of the laser pulse in the CVL is due not only to filling of the lower laser level, but also to a reduction in the upper laser-level pumping related to the collapse of power input to the plasma during the excitation pulse. Time-resolved measurements of excited-state densities over a wide range of input-power conditions clearly illustrate that the increase in copper density with power input reduces the peak electron temperature in the plasma during the excitation pulse. This reduction in peak electron temperature is important in limiting the scaling of CVL output power with input-power-copper density     

Model of temperature dependence for gain shape of erbium-dopedfiber amplifier

The problem of modeling the temperature dependence of erbium-doped fiber amplifier (EDFAs) is important for multichannel optical WDM systems. A physical model is presented in this paper, which could be used to predict the gain change under temperature variations for such systems. Some of the input parameters for the model are the erbium energy sublevel density, excitation coefficients from lower sublevels to upper sublevels of erbium ions, and electron distribution over energy levels. It is difficult to measure these parameters. In order to use the model for gain shape calculations, some simplifications are demonstrated. These simplifications lead to two numerical models, which are shown to be consistent with experimental data with reasonable accuracy, and are based only on two spectral measurements for different temperatures. Both numerical models were tested for the signal band and the 980 nm pump band of a typical erbium-doped fiber     

瞬态C-V法测量AlGaAs:Si中DX中心的电离能(英文)

The thermal ionization energy ET of DX centers in AlxGa1-xAs and its dependence with the value of x and the pressure are very important for estab- lishing the model of DX centers. The conventional DLTS and Hall methods used to DX center measurement have some ambiguities in theoretical analysis and experiments and the values of ET determined are different with those methods. The new constant temperature transient C-V measurement is based on the fact that at low temperature both electron capture and emission rates of DX centers are very slow. During the transient C-V measurement, change; of bias voltages and capacitance measurements are completed in a time duration much shorter than the electron capture and emission time constants, therefore the electrons occupied on the DX centers are considered to be frozen. The density of DX centers, the distribution profile of electrons on DX centers in the depletion region of a Schottky diode at a constant reverse bias, and the density of free electrons in conduction band in the bulk and their temperature dependence have been measured.     

Radar backscatter from the earth's ionosphere

The role of radar backscatter observations in ionospheric studies is outlined. The theoretical developments are described that form the basis for ground-based measurements of electron density, electron temperature, ion temperature, and ionic composition at ionospheric heights, Observations of the first three parameters have been successful. Observation of the fourth parameter, ionic composition, is a challenging problem and is being attempted.     

一种新颖的三角波扫频式微波干涉仪及信号处理方法研究

分析了一种三角波扫频式微波干涉仪的工作原理,并依据其原理设计了一种8mm微波干涉仪系统来测量等离子体电子密度。讨论了这种微波干涉仪系统的信号处理依据及其实现方法,并分析了其相位测量理论误差。为了验证该微波干涉仪的测量结果可靠性,采用与矢量网络分析仪测量开关移相器的测试结果比较、对日光灯的脉动等离子体测试结果与国外数据比对等不同的方法,证明了三角波扫频式微波干涉仪系统设计思想正确、测量数据可靠、测量精度高。     

Low-field bulk defect generation during uniform carrier injection into the gate insulator of insulated gate field effect transistors at various temperatures

Low-field electron injection of up to 10¹⁹ e/cm² across the Si-SiO₂ interface into the gate insulator of an n-channel insulated gate field effect transistor using an optically assisted hot electron injection technique was conducted from room temperature down to 100K. It was found that the room temperature data could be modeled quite accurately by attributing all of the observed ΔV_t to generation of negatively charged defects whose generation follows a power law. At reduced temperatures, “structure” in the observed data indicated the presence of one shallow first order trap. In this case, a combination of a power law generation term and a single first order trap cross section was used, and is needed, to accurately model the data. It was also found that trap generation is enhanced significantly as the temperature is reduced. Threshold voltage shifts were shown by charge pumping measurements not to be associated with interface state generation under the low-field conditions employed. The results presented here indicate that even at very low applied oxide fields (1 MV/cm) hot electron injection not only results in the filling of existing traps, but also in the generation of new charged bulk defects whose generation rate increases as the temperature is reduced, or the injection current density is increased. These results also raise questions about some of the reports of small cross section trapping centers, ≤10⁻¹⁷ cm², since these were typically characterized by applying a only first order trapping model to high field and/or high current density injection data. Such aggressive injection conditions could very easily have resulted in the generation of charged bulk defects which could then be erroneously identified as one or more small cross section traps.     

Experimental investigation of the temperature dependence of GaAsFET equivalent circuits

Accurate 13-element temperature-dependent RF equivalent circuits have been extracted from on-wafer S-parameter measurements of ion implanted and epitaxially grown recess-gate MESFETs and HEMTs at many biases for temperatures from -70 to +110°C. The variations in each equivalent circuit element are expressed by a linear function of temperature. The temperature coefficients are bias- and technology-dependent. These data can be used to predict RF circuit performance variations with temperature. It is used to deduce the temperature dependence of physical factors such as electron mobilities and saturated velocities and the Schottky-barrier height     

Fermi's golden rule, nonequilibrium electron capture from the wetting layer, and the modulation response in P-doped quantum-dot lasers

Electron capture from a quantum dot's (QDs) wetting layer is described by Fermi's golden rule that relates the transition rate to the density of final states. The wetting layer capture causes a brief nonequilibrium electron distribution between the QD ground state and its wetting layer states and can slow a QD laser's modulation response. This effect is studied for time constants and capture conditions relevant to self-organized InAs QDs. It is shown that even a moderately fast electron capture consistent with present low temperature measurements can limit a QD laser's modulation speed.     

The combined use of satellite differential Doppler and ground-based measurements for ionospheric studies

The use of satellite differential Doppler measurements to study latitudinal variations ofF-region electron density is described. It is shown that the ambiguity in the total phase path length may be resolved employing either incoherent scatter radar measurements or vertical-incidence ionosonde data, together with some assumptions concerning east-west gradients at the latitude of the observing station. Sample results are given showing the location of the midlatitude trough of electron density observed at Millstone Hill through observations of the U.S. Navy Navigation Series satellites.