Avalanche multiplication noise characteristics in thin GaAs p+-i-n+ diodes

Avalanche noise measurements have been performed on a range of homojunction GaAs p⁺-i-n⁺ and n⁺-i-p ⁺ diodes with “i” region widths, ω from 2.61 to 0.05 μm. The results show that for ω⩽1 μm the dependence of excess noise factor F on multiplication does not follow the well-established continuous noise theory of McIntyre [1966]. Instead, a decreasing noise factor is observed as ω decreases for a constant multiplication. This reduction in F occurs for both electron and hole initiated multiplication in the thinner ω structures even though the ionization coefficient ratio is close to unity. The dead-space, the minimum distance a carrier must travel to gain the ionization threshold energy, becomes increasingly important in these thinner structures and largely accounts for the reduction in noise     

Photocurrent multiplication in GaAs Schottky photodiodes

Many attempts have been made to build fast, sensitive photodetectors which offer simple fabrication and ease of integration. Regarding this view, GaAs Schottky barrier photodiodes seem to be ideally suited for use in the near-infrared region. The fabrication of GaAs Schottky photodiodes and the investigation of their properties (mainly photocurrent multiplication) are presented in this paper. A photocurrent gain of 10⁴ was achieved and dependences of gain on incident power level and position were observed.     

Correlation measurement of carrier multiplication noise sources inMOS transistors at low frequencies

Low frequency techniques of cross spectrum and correlation coefficient measurements are presented and applied to investigate drain and substrate noises of MOS transistors when multiplication occurs in the channel. For low substrate currents it is shown that the experimental data agree with theoretical expectations: the correlation coefficient is maximum at low frequencies and reaches its minimum value which is only dependent of the multiplication factor in the upper frequency range. For high substrate currents uncorrelated 1/f noise appears in bulk conductance     

Low-frequency multiplication noise in reference diodes for small multiplication factors

An analysis of the current dependence of multiplication noise for small multiplication factors (M < 103) is given, including the generation component of the reverse current and the position dependence of the ionisation coefficient of electrons (and holes) in the diode depletion region. Results are given for abrupt Si p?n junctions.     

Voltage measurement in GaAs Schottky barriers using optical phasemodulation

What are thought to be the first measurements of applied voltage in a GaAs Schottky-barrier diode using optical phase modulation are presented. A theoretical model, based on the refractive-index perturbation in a Schottky-barrier depletion region, describing these measurements was derived and gives good agreement with the observe results. The large signal response and large frequency response of the measurement system are illustrated. This technique facilitates high-sensitivity measurements of voltages in integrated Schottky diodes     

Narrow pulse measurement of drain characteristics of GaAs MESFETs

A measurement technique is presented which uses narrow, fast-rise-time pulses applied to both the gate and the drain of a GaAs MESFET to obtain the drain characteristics of the device. This allows the characteristics of the device to be obtained which correspond to frequencies above those at which surface and substrate traps can respond. The resulting characteristics show significant departures from those obtained using conventional long pulse and DC measurement techniques.     

Pressure measurement by GaAs piezoelectric sensors

A new pressure sensor for pressures up to 100 bar and temperatures of about 200 degrees C is presented. It uses the piezoelectric effect of 111 oriented semi-insulating GaAs. This material allows the monolithic integration of sensor and electronic circuit.<>     

Avalanche multiplication in GaInP/GaAs single heterojunctionbipolar transistors

The electron multiplication factors in GaInP/GaAs single heterojunction bipolar transistors (HBT's) have been measured as a function of base-collector bias for a range of GaAs collector doping densities. In the lowest doped (5×10¹⁴ cm^-3) thick collector the multiplication is determined by the local electric field. As the collector doping increases, the measured multiplication is found to be significantly reduced at low values of multiplication from that predicted by the electric field profile. However, good agreement is always found at high multiplication, close to breakdown. This reduction in multiplication at low electric fields is attributed to the dead space, the minimum distance over which carriers must travel before gaining the ionization threshold energy. A simple correction for the dead space is proposed, allowing the multiplication to be accurately predicted even in heavily doped structures     

Low-frequency diffusion noise in GaAs MESFET's

We report here on low-frequency diffusion noise of GaAS MESFET's. The Poole-Frenkel effect gives a shift of the corner frequency (f = D/πL²). From the measurements the activation energy of the diffusing ions is found to be 0.16 eV. At 77 K the diffusion noise is frozen out and the device has a 1/f spectrum.     

Thermal noise measurements in GaAs MESFET's

The absolute magnitude of the thermal drain current fluctuations and the associated effective thermal noise coefficient of 1-µm gate-length MESFET's have been measured under various bias conditions. At low drain-source voltages the magnitude of current fluctuations are in good agreement with the thermal noise theory which is based on the gradual channel approximation. However, under normal operating conditions (V_{ds} geq 1.5V,V_{gs} approx 0), we find for the thermal drain noise currentimin{d}max{2} approx 1 - 2 times 10^{-22}A²/Hz with a noise coefficientP approx 0.1in disagreement with the commonly used, theoretically predicted value P = 1.1. Our results are qualitatively consistent with a more comprehensive FET noise theory which properly takes into account high-field effects.     

Low-frequency noise in GaAs current limiters

The theory of the one-dimensional diffusion noise is modified and applied to explain the low frequency noise in GaAs current limiters. The devices show noise spectra with $\text{f}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$ and $\text{f}{}^{\mathrm{<mtext>?</mtext><mtext>3</mtext><mtext>2</mtext>}}$ branches. The turn-over frequency increases with the applied voltage and temperature increase. The diffusion constant depends exponentially on temperature and the activation energy varies with electric field because of Poole-Frenkel effect. The experimental data confirms the temperature and voltage dependence of noise. The calculated activation energy is very close to the value reported in connection with leakage current in GaAs MESFET. Since the diffusion constant differs by many orders of magnitude from diffusion constant of electrons or ions one-dimensional diffusion of ions along dislocation lines is proposed. However, the mechanism of diffusion is not fully understood yet.     

基于自适应卡尔曼滤波的光纤陀螺噪声系数估计方法

针对Allan方差法确定光纤陀螺ARW（angle random walk）噪声系数的一些不足,如大量存储数据、非实时处理、计算量大、耗时长等,提出了基于自适应卡尔曼滤波的光纤陀螺ARW系数在线估计方法.在角度随机游走、零偏不稳定性、角速率随机游走等主要噪声数学特性分析基础上,建立了光纤陀螺现代状态空间噪声误差模型,基于新息自适应卡尔曼滤波量测噪声协方差阵的迭代计算,实现光纤陀螺ARW系数的在线、实时估计,从而避免了存储大量历史数据,显著地减小了计算量,缩短了陀螺数据处理时间.数字仿真试验和光纤陀螺实测数据试验结果均验证了本文方法的可行性和有效性.     

Temperature dependence of multiplication noise in silicon avalanche photodiodes

The temperature dependence of multiplication noise in silicon avalanche photodiodes with a low-high-low impurity density profile is calculated. The variation of multiplication noise by temperature change can be neglected in practical use at a constant multiplication factor, which is in agreement with experimental results.     

A Monte Carlo investigation of multiplication noise in thin p+-i-n+ GaAs avalanche photodiodes

A Monte Carlo (MC) model has been used to estimate the excess noise factor in thin p⁺-i-n⁺ GaAs avalanche photodiodes (APD's). Multiplication initiated both by pure electron and hole injection is studied for different lengths of multiplication region and for a range of electric fields. In each ease a reduction in excess noise factor is observed as the multiplication length decreases, in good agreement with recent experimental measurements. This low noise behavior results from the higher operating electric field needed in short devices, which causes the probability distribution function for both electron and hole ionization path lengths to change from the conventionally assumed exponential shape and to exhibit a strong dead space effect. In turn this reduces the probability of higher order ionization events and narrows the probability distribution for multiplication. In addition, our simulations suggest that fur a given overall multiplication, electron initiated multiplication in short devices has inherently reduced noise, despite the higher feedback from hole ionization, compared to long devices     

Wavelength dependence of multiplication noise in silicon avalanche photodiodes

Theoretical and experimental results on wavelength dependence of multiplication noise in silicon avalanche photodiodes are described. When the photodiode has a p-n⁺-junction and is illuminated from the n⁺-side, multiplication noise increases by decreasing optical wavelength. Effective ionization coefficient ratio keffis equal tokexp (2Kw_{a}) for a uniform junction electric field, wherekis the ratio of ionization coefficients of electrons α and holes β. The multiplication noise depends on the product of optical absorption coefficientKand the avalanche-region width wa. Calculations show that there exists an optimum wafor minimizing multiplication noise at a given wavelength. Theoretical results are shown to agree with results of experiments on diodes with a low-high-low impurity profile. Measured ionization coefficient ratiokvalues are 0.04 and 0.08 at 0.811- and 0.633-µm wavelength, respectively.     

Approximate values of the multiplication coefficient in one-sided abrupt junctions

In this paper, a simple method is proposed for calculating the multiplication coefficient M in abrupt one-sided junctions near the breakdown. The empirical law of S.L. Miller [1]:

$\text{1?}\text{1}\text{M}\text{=}\text{V}\text{V}{}_{\mathrm{B}}{}^{\mathrm{n}}$

V_B breakdown voltage is taken as the first term of a series expansion near the breakdown of the function 1?(1/M), the value of the exponent n being linked to the physical parameters of the junction and to the type (electron or hole) of the incident carrier. The method is developed for several different materials: Ge, GaAs, GaP, Si using well established data for ionization rates. The values of the multiplication coefficient given by the approximation is compared to the computed exact values obtained by the calculation of the ionization integrals. We found that the approximation is correct with an accuracy of ±10% for a large variation of the ratio V/V_B.     

Avalanche noise characteristics of thin GaAs structures withdistributed carrier generation [APDs]

It is known that both pure electron and pure hole injection into thin GaAs multiplication regions gives rise to avalanche multiplication with noise lower than predicted by the local noise model. In this paper, it is shown that the noise from multiplication initiated by carriers generated throughout a 0.1 μm avalanche region is also lower than predicted by the local model but higher than that obtained with pure injection of either carrier type. This behavior is due to the effects of nonlocal ionization brought about by the dead space; the minimum distance a carrier has to travel in the electric field to initiate an ionization event     

Low noise 5 GHz differential VCO using InGaP/GaAs HBT technology

The authors present the first InGaP/GaAs HBT differential VCOs with low phase noise performance. One is a cross coupled differential VCO, and the other is a Colpitts differential VCO. To achieve a fully integrated VCO, collector-base junction capacitance of HBT transistor is used for the frequency tuning varactor. The measured output frequency ranges of VCOs are 290 MHz and 190 MHz, and the phase noises at an offset frequency of 1 MHz are -118 dBc/Hz and -117 dBc/Hz respectively. The each VCO core dissipates 13.2 mW from a 3.5 V supply, and the output power is about -0.2 dBm. Concerned with cross coupled VCO, it shows the figure of merit of -179 dBc/Hz, which is the best result among the reported compound semiconductor FET and HBT VCOs.     

Analysis of noise margin and speed of GaAs MESFET DCFL using UM-SPICE

Using a customized GaAs IC circuit simulator (UM-SPICE) the design trade-offs and process sensitivity of the logic levels, noise margin, and propagation delay for GaAs direct coupled field effect logic (DCFL) gates are analyzed. The results of the circuit simulation are shown to be in good agreement with our experimental data. For DCFL gates with ungated FET loads studied here, the noise margin is found to be the more important design criteria. The noise margin is a sensitive function of both the driver-to-load current ratio and the driver threshold voltage, whereas the propagation delay remains fairly constant over a wide range of driver-to-load ratios and threshold voltages. Our simulations indicate that a driver-to-load ratio of about 5 and a threshold voltage of about 0.1 V would offer the optimum performance for most applications. Also, the DCFL design with shallow channel transistor appears to be less sensitive to the substrate or implantation variations.