On the RF Extrinsic Resistance Extraction for Partially-Depleted SOI MOSFETs

We have investigated the radio frequency (RF) extrinsic resistance extraction for partially-depleted (PD) silicon-on-insulator (SOI) metal-oxide-semiconductor field effect transistors (MOSFETs). Although the thick buried oxide in SOI devices can block the substrate coupling, the SOI neutral-body coupling effect is significant for RF applications. An equivalent circuit considering this effect has been proposed. Based on this equivalent circuit, a new model capturing the frequency dependence of extrinsic resistances has been derived. After considering the impact of quasi-neutral body, we have developed a physically accurate RF extrinsic resistance extraction methodology for PD SOI MOSFETs     

Cryogenic operation of third-generation, 200-GHz peak-f/sub T/, silicon-germanium heterojunction bipolar transistors

We present a comprehensive investigation of the cryogenic performance of third-generation silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technology. Measurements of the current-voltage (dc), small-signal ac, and broad-band noise characteristics of a 200-GHz SiGe HBT were made at 85 K, 120 K, 150 K, 200 K, and 300 K. These devices show excellent behavior down to 85 K, maintaining reasonable dc ideality, with a peak current gain of 3800, a peak cut-off frequency (f/sub T/) of 260 GHz, a peak f/sub max/ of 310 GHz, and a minimum noise figure (NF/sub min/) of approximately 0.30 dB at a frequency of 14 GHz, in all cases representing significant improvements over their corresponding values at 300 K. These results demonstrate that aggressively scaled SiGe HBTs are inherently well suited for cryogenic electronics applications requiring extreme levels of transistor performance.     

A study of on-resistance and switching characteristics of the power MOSFET under cryogenic conditions

The decrease in on-resistance of power MOSFETs operation under cryogenic temperature leads to a considerable reduction in heat generation inside the device. An experimental measurement of on-resistances at 77K, 173K, 243K and 295K was carried out by applying cryogenic cooling techniques. The decrease in on-resistance and capacitance associated with the temperature led to an enhancement of overall time response of the MOSFETs. Another advantage associated with operating MOSFETs under cryogenic temperature is the decrease of the internal thermal resistance. The present work demonstrated that by exposing the device to cryogenic conditions, it is possible to implement high frequency, high power applications with MOSFET devices.     

RF power characteristics of SiGe HBTs at cryogenic temperatures

This paper investigates the temperature dependence (from 77 to 300 K) of dc, ac, and power characteristics for n-p-n SiGe heterojunction bipolar transistors (HBTs) with and without selectively implanted collector (SIC). In SiGe HBTs without SIC, the valance band discontinuity at the base-collector heterojunction induces a parasitic conduction band barrier while biasing at saturation region and high current operation at cryogenic temperatures. This parasitic conduction band barrier significantly reduces the current gain and cutoff frequency. For transistors biased with fixed collector current, the measured output power, power-added efficiency, and linearity at 2.4 GHz decrease significantly with decreasing operation temperatures. The temperature dependence of output power characteristic is analyzed by Kirk effect, current gain, and cutoff frequency at different temperatures. The parasitic conduction band barrier in SiGe HBTs with SIC is negligible, and thus the device achieves better power performance at cryogenic temperatures compared with that in SiGe HBT without SIC.     

GaAs slow-wave phase shifter characteristics at cryogenic temperatures

It has been previously demonstrated that a single elemental solid-state GaAs epitaxial device, based on slow-wave electromagnetic propagation, can provide substantial variable phase shift in the microwave frequency regime at room temperature. Further, it has been shown that the insertion loss L of the device is reduced by increasing the conductivity in the transmission line metallization. Low-temperature applications make it desirable to determine if such a device can operate at cryogenic temperatures demonstrating useful phase-shifting properties. We have developed an accurate reliable cryogenic experimental test setup and procedure capable of measuring the phase shift θ and insertion loss L of a 1.6-mm-long device embedded in a waveguide system several meters long. Measurements have been made at 4.2, 77, and 309 K over a frequency range from 2 to 18 GHz. The 300-K results agree extremely well with earlier work and substantiate that very accurate measurements in such a setup are possible. The cryogenic results at 77 K produce a differential phase shift of 155° compared to 229° at 300 K. Loss reduction is most dramatic at frequencies below about 14 GHz and becomes progressively less as 18 GHz is approached. For example, at a Schottky bias voltage of 0.5 V, L is reduced by a factor of 2.3, 2.2, and 2.4 at 2, 10, and 12 GHz, respectively. Similar loss reduction factors are found up to 14 GHz for the 0.0-V bias case. Device operation at 4.2 K produces a differential phase shift of 206° and not much change in loss values compared to 77 K.     

Low-temperature microwave characteristics of pseudomorphic InxGa1-xAs/In0.52Al0.48Asmodulation-doped field-effect transistors

Low-temperature microwave measurements of both lattice-matched and pseudomorphic In_xGa_1-xAs/In_0.48As (x=0.53, 0.60, and 0.70) channel MODFETs on InP substrates were carried out in a cryogenic measurement system. The measurements were done in the temperature range of 77 to 300 K and in the frequency range of 0.5 to 11.0 GHz at different bias conditions. The cutoff frequency ( f_T) for the In_xGa_1-xAs/In_0.52Al_0.48As MODFETs improved from 22 to 29 GHz, 29 to 38 GHz, and 39 to 51 GHz, for x=0.53, 0.60, and 0.70, respectively, as the temperature was lowered from 300 to 77 K, which is approximately a 31% increase at each composition. No degradations were observed in device performance. These results indicate an excellent potential of the pseudomorphic devices at low temperatures     

Low-Noise Cooled GASFET Amplifiers

Measurements of the noise characteristics of a variety of gallium-arsenide field-effect transistors at a frequency of 5 GHz and temperatures of 300 K to 20 K are presented. For one transistor type detailed measurements of dc parameters, small-signal parameters, and all noise parameters (T/sub min/, R/sub opt/, X/sub opt/ g/sub n/) are made over this temperature range. The results are compared with the theory of Pucel, Haus and Statz modified to include the temperature variation. Several low-noise ampifiers are described including one with a noise temperature of 20 K over a 500-MHz bandwidth. A theoretical analysis of the thermal conduction at cryogenic temperatures in a typical packaged transistor is included.     

Window materials for high power gyrotron

The room temperature application of sapphire as window material at higher frequencies is not feasible since its absorption coefficient increases almost linearly with increasing frequency in the millimeter wavelength region. At cryogenic temperature the absorption coefficient value decreases only by a few factors (factor of 2 to 3) in the 90 – 200 GHz region. The earlier reported temperature squared dependence (decrease) in the absorption coefficient or the loss tangent value is totally absent in our broad band continuous wave data we are reporting here (at 6.5 K, 35K, 77K and 300K) and one we reported at conferences earlier. Our results are verified by another technique. We utilize our precision millimeter wave dispersive Fourier transform spectroscopic techniques at room temperature and at cryogenic temperatures The extra high resistivity single crystal compensated silicon is no doubt the lowest loss material available at room temperature in the entire millimeter wavelength region At higher millimeter wave frequencies an extra high resistivity silicon window or an window made with extra high resistivity silicon coated with diamond film would certainly make a better candidate in the future. A single free standing synthetic diamond window seems to have higher absorption coefficient values at millimeter wavelength region at this time although it is claimed that it possesses good mechanical strength and higher thermal conductivity characteristics. It certainly does not rule out the use of diamond film on a single crystal high resistivity silicon to improve its mechanical strength and thermal conductivity     

Cryogenic temperature performance of modulation-doped field-effect transistors

Reports S-parameter measurements of AlInAs/GaInAs/InP modulation-doped field-effect transistors (MODFETs) at cryogenic temperatures. The current gain at 80 K is 3 dB higher than at 300 K, and the current gain cutoff frequency f/sub T/ increases from 32 GHz at 300 K, to 42 GHz at 80 K, which is the first observation of higher f/sub T/ by direct measurement.<>     

AC behavior of gate-induced floating body effects in ultrathin oxide PD SOI MOSFETs

In this letter we present for the first time an ac analysis of the gate-induced floating body effects (GIFBE) occurring in ultrathin gate oxide partially depleted (PD) silicon-on-insulator (SOI ) MOSFETs due to tunneling gate current. A simple equivalent circuit is proposed, which indicates that the ac behavior of GIFBE is related to the small-signal voltage variations of the floating body region. It also shows that due to the high impedance seen by the body region toward the external nodes, the GIFBE frequency dependence is characterized by a very low cut off frequency (< a few kilohertz), which is consistent with experimental data and circuit simulations performed with BSIMSOI.     

Temperature dependence of hot-carrier degradation in silicon-on-insulator dynamic threshold voltage MOS transistors

The authors analyze the influence of temperature on hot-carrier degradation of silicon-on-insulator (SOI) dynamic threshold voltage MOS (DTMOS) devices. Both low and high stress gate voltages are used. The temperature dependence of the hot-carrier effects in DTMOS devices is compared with those in SOI partially depleted (PD) MOSFETs. Possible physical mechanisms to explain the obtained results are suggested. This work shows that even if the stress gate voltage is low, the degradation of DTMOS devices stressed at high temperature could be significant.     

L 波段宽带低温低噪声放大器的设计与测量*

高电子迁移率晶体管(HEMT)的小信号等效电路低温模型是研制致冷低噪声放大器(LNA)与研究晶 体管微波特性的基础。该文通过测量HEMT 器件在低温环境下直流参数与散射参数(S 参数),构建了包含噪声参 量的小信号等效电路,并据此设计了一款覆盖L 波段的宽带低温低噪声放大器(LNA),工作频率1 ~2GHz,相对带宽 达到66. 7%。在常温下放大器功率增益大于28dB,噪声温度小于39K;当环境温度制冷至11K 时,噪声温度为1. 9 ~3. 1K,输入输出端口的回波损耗S11 和S22 均优于-10dB,1dB 压缩点输出功率为9. 2dBm,功耗仅为54mW。     

Low-Voltage and High-Speed Operations of 30-nm-Gate Pseudomorphic $hbox{In}_{0.52}hbox{Al}_{0.48}hbox{As}/hbox{In}_{0.7}hbox{Ga}_{0.3} hbox{As}$ HEMTs Under Cryogenic Conditions

In this letter, we fabricated 30-nm-gate pseudomorphic In_0.52 Al_0.48As/In_0.7Ga_0.3As HEMTs with multilayer cap structures to reduce source and drain parasitic resistances; we measured their dc and radio-frequency characteristics at 300, 77, and 16 K under various bias conditions. The maximum cutoff frequency fT was 498 GHz at 300 K and 577 GHz at 77 K. The maximum fT exceeded 600 GHz at 16 K. Even at a drain-source voltage V _ds of 0.4 V, we obtained an fT of 500 GHz at 16 K. This indicates that cryogenic HEMTs are favorable for low-voltage and high-speed operations. Furthermore, the present 30-nm-gate HEMTs at 300 K show almost the same fT values at the same dc-power dissipation as compared to 85-nm-gate InSb-channel HEMTs. The improvement of the maximum-oscillation-frequency f _max values was also observed at 77 and 16 K.     

Short-channel-effect free 0.18 μm MOSFET bytemperature-dimension combination scaling theory: design and experiment

We have fabricated 77 K deep-submicron MOSFETs on the basis of the temperature-dimension combination scaling theory (CST). The 77 K MOSFETs with 1-V supply voltage are designed from a 300 K MOSFET with 4-V supply voltage. The fabricated 77 K 0.18 μm device has exhibited fully scaled characteristics. The subthreshold swing (S) and the threshold voltage (V_th) of the 77 K device are found to be 1/4≈77 K/300 K of those of the 300 K device. Furthermore, S and V_th are achieved to be 27 mV/dec and 0.21 V without short-channel effect degradation     

The kink-related excess low-frequency noise in silicon-on-insulatorMOST's

The phenomenology of the kink-related low-frequency (LF) noise overshoot in partially depleted (PD) silicon-on-insulator (SOI) MOS transistors is described in detail. The influence of various physical parameters is reported. Based on the observations, a comprehensive first-order theory for the feature is derived. The model is based on the charge fluctuations which are caused by deep-level assisted generation-recombination events in the depletion region of the transistor. It will be shown that the noise amplitude is proportional to the density of deep-level centers, while the peak position is a sensitive function of the saturation voltage. This follows from the postulated dependence of the capture time on the inverse substrate current. As will be shown, the standard expression for the multiplication current is in first order also valid for SOI MOST's, both at room temperature and at 77 K. Simulations demonstrate that the proposed model correctly predicts the dependence of the noise overshoot on the measurement frequency, on the gate voltage, the temperature and on the device length. Finally, the spectroscopic potential of the feature will be outlined and possible ways to render the technique truly quantitative are pointed out     

Drain noise in MOSFETs at zero drain bias as a function of temperature

The noise in MOSFETs at zero drain bias is found to be somewhat larger than the thermal noise of the output conductance g_do at that bias. The effect is most pronounced at 300°K and has practically disappeared at 77°K. The effect is attributed to the large transverse field at the surface of the channel; the temperature dependence of the effect is as yet unexplained.     

History dependence of output characteristics ofsilicon-on-insulator (SOI) MOSFETs

It is demonstrated that the drain current overshoot in partially depleted SOI MOSFETs has a significant history dependence or memory effect, even in the absence of impact ionization under low drain biases. The measured output characteristics of partially depleted SOI MOSFETs are shown to be dynamically dependent on their switching history, frequency, and bias conditions, due to the finite time constants of carrier generation (thermal or impact ionization) and recombination in the floating body     

Accurate SOI MOSFET characterization at microwave frequencies fordevice performance optimization and analog modeling

The maturation of low-cost silicon-on-insulator (SOI) MOSFET technology in the microwave domain has brought about a need to develop specific characterization techniques. An original scheme is presented, which, by combining careful design of probing and calibration structures, rigorous in situ calibration, and a new powerful direct extraction method, allows reliable identification of the parameters of the non-quasi-static (NQS) small-signal model for MOSFETs. The extracted model is shown to be valid up to 40 GHz     

Accurate Characterization of Silicon-On-Insulator MOSFETs for the Design of Low-Voltage, Low-Power RF Integrated Circuits

The maturation of low cost Silicon-on-Insulator (SOI) MOSFET technology in the microwave domain has brought about a need to develop specific characterization techniques. An original scheme is presented, which, by combining careful design of probing and calibration structures, rigorous in-situ calibration, and a new powerful direct extraction method, allows reliable identification of the parameters of the non-quasi-static small-signal model and the high-frequency noise parameters for MOSFETs. The extracted model is shown to be valid up to 40 GHz.     

Characteristics of GaAs/AlGaAs-doped channel MISFET's at cryogenictemperatures

High-frequency measurements at cryogenic temperatures to 125 K of 0.3-μm gate length GaAs-Al_0.3Ga_0.7As metal-insulator-semiconductor field-effect transistors (MISFETs) with a doped channel are discussed. Experimental results demonstrate significant improvement in performance including an increase in the maximum frequency of oscillation from 70 to 81 GHz and an increase in the unity current gain cutoff frequency from 46 to 57 GHz. Independently determined decreases in electron mobility and increases in electron velocity under similar conditions lead to the conclusion that carrier velocity and not mobility controls transport in these devices. These results show the high-speed potential of doped channel MISFETs at both room temperature and cryogenic temperatures