Deep Cryogenic Temperatures Research Articles

The Cryogenic Temperature Behavior of Bipolar, MOS, and DTMOS Transistors in Standard CMOS

Both CMOS bandgap voltage references and temperature sensors rely on the temperature behavior of either CMOS substrate BJTs or MOS transistors in weak inversion. Bipolar transistors are generally preferred over MOS transistors because of their lower spread. However, at deep-cryogenic temperatures, the performance of BJTs deteriorates due to a significant reduction in current gain and a substantial increase in the base resistance. On the contrary, MOS devices show more stable performance even down to 4 K, but accurate device characterization for the design of such a circuit is currently missing. We present the characterization and analysis over the temperature range from 4 K to 300 K of both substrate bipolar PNP transistors and MOS transistors in standard and dynamic threshold MOS (DTMOS) configurations implemented in a standard 0.16- $\mu \text{m}$ CMOS technology. These results demonstrate that employing MOS or DTMOS enables the operation of bandgap references and temperature sensors in standard CMOS technologies even at deep-cryogenic temperatures.

High-Quality Factor Superconducting Flexible Resonators Embedded in Thin-Film Polyimide HD-4110

We present the design, fabrication procedure, and measurement results of Nb superconducting microstrip transmission line resonators fabricated using thin-film polyimide HD-4110, including both nonembedded and embedded versions. These resonators were used to characterize the microwave dielectric loss tangent of 20 $\mu$ m thick polyimide HD-4110 at deep cryogenic temperatures. We observed high-quality factors ( Q ) up to 21 040 at 1.2 K in the frequency range of 2–21 GHz for nonembedded resonators, indicating that the dielectric loss tangent can be less than 5 $\times$ 10−5. Embedded resonators with an additional 20 $\mu$ m thick encapsulation layer also exhibited Q values as high as $\sim 19$ 200. Dielectric and conductor (quasiparticle) loss have been compared between the two types of resonators. This study provides information applicable to the design of future high-density, flexible, multilayer superconducting cables, which are of great interest for potential applications in cryogenic electronics systems, including quantum computers.

Constitutive Models for the Viscoelastic Behavior of Polyimide Membranes at Room and Deep Cryogenic Temperatures

Targets for inertial confinement fusion shots on the National Ignition Facility typically use thin polyimide films, ~500 nm, with a coating of 25 nm of aluminum as windows that seal the laser entrance hole. Their role is to contain the hohlraum gas and minimize the extraneous infrared radiation getting in. This is necessary to control precisely the hohlraum thermal environment for layering inside the capsule with solid deuterium-tritium at 18 K. Here, we use our empirical data on the bulging behavior of these foils under various different conditions to develop models to capture the complex viscoelastic behavior of these films at both room and cryogenic temperatures. The constitutive equations derived from these models give us the ability to quantitatively specify the film’s behavior during the fielding of these targets and set the best parameters for new target designs.

Flexible superconducting Nb transmission lines on thin film polyimide for quantum computing applications

We describe progress and initial results achieved towards the goal of developing integrated multi-conductor arrays of shielded controlled-impedance flexible superconducting transmission lines with ultra-miniature cross sections and wide bandwidths (dc to >10 GHz) over meter-scale lengths. Intended primarily for use in future scaled-up quantum computing systems, such flexible thin-film niobium/polyimide ribbon cables could provide a physically compact and ultra-low thermal conductance alternative to the rapidly increasing number of discrete coaxial cables that are currently used by quantum computing experimentalists to transmit signals between the several low-temperature stages (from ∼4 K down to ∼20 mK) of a dilution refrigerator. We have concluded that these structures are technically feasible to fabricate, and so far they have exhibited acceptable thermo-mechanical reliability. S-parameter results are presented for individual 2-metal layer Nb microstrip structures having 50 Ω characteristic impedance; lengths ranging from 50 to 550 mm were successfully fabricated. Solderable pads at the end terminations allowed testing using conventional rf connectors. Weakly coupled open-circuit microstrip resonators provided a sensitive measure of the overall transmission line loss as a function of frequency, temperature, and power. Two common microelectronic-grade polyimide dielectrics, one conventional and the other photo-definable (PI-2611 and HD-4100, respectively) were compared. Our most striking result, not previously reported to our knowledge, was that the dielectric loss tangents of both polyimides, over frequencies from 1 to 20 GHz, are remarkably low at deep cryogenic temperatures, typically 100× smaller than corresponding room temperature values. This enables fairly long-distance (meter-scale) transmission of microwave signals without excessive attenuation, and also permits usefully high rf power levels to be transmitted without creating excessive dielectric heating. We observed loss tangents as low as 2.2 × 10−5 at 20 mK, although losses increased somewhat at very low rf power levels, similar to the well-known behavior of amorphous inorganic dielectrics such as SiO2. Our fabrication techniques could be extended to more complex structures such as multiconductor cables, embedded microstrip, 3-metal layer stripline or rectangular coax, and integrated attenuators and thermalization structures.

Effects of deep cryogenic treatment, cryogenic and annealing temperatures on mechanical properties and corrosion resistance of AA5083 aluminium alloy

Effects of deep cryogenic treatment (DCT), cryogenic and annealing temperatures on micro-structural evolution, mechanical properties and the intergranular corrosion (IGC) resistance of AA5083 aluminium alloy are investigated. Results showed that as the temperature of the annealing increased, its strength decreased while the IGC resistance improved. At cryogenic temperature, strength and ductility increased drastically. Failure modes observed were ductile particle dimples at 295 K and 213 K, and a mixture of intergranular and transgranular fractures at 110 K. Specimens annealed at 150°C and 200°C exhibited a higher vulnerability to IGC due to the presence of high dislocation densities and heterogeneous precipitation of β-phase (Al3Mg2) at the grain boundaries as the continuous phase. In contrast, specimens annealed from 250°C to 415°C exhibited excellent corrosion resistance due to the minimisation of dislocation densities and noncontinuous distribution of β-phase. DCT marginally decreased the strength and hardness of the alloy, while increasing the ductility and IGC resistance.

An FPGA-based instrumentation platform for use at deep cryogenic temperatures.

We describe the operation of a cryogenic instrumentation platform incorporating commercially available field-programmable gate arrays (FPGAs). The functionality of the FPGAs at temperatures approaching 4 K enables signal routing, multiplexing, and complex digital signal processing in close proximity to cooled devices or detectors within the cryostat. The performance of the FPGAs in a cryogenic environment is evaluated, including clock speed, error rates, and power consumption. Although constructed for the purpose of controlling and reading out quantum computing devices with low latency, the instrument is generic enough to be of broad use in a range of cryogenic applications.

Strong Isotope Effects on Melting Dynamics and Ice Crystallisation Processes in Cryo Vitrification Solutions

The nucleation and growth of crystalline ice during cooling, and further crystallization processes during re-warming are considered to be key processes determining the success of low temperature storage of biological objects, as used in medical, agricultural and nature conservation applications. To avoid these problems a method, termed vitrification, is being developed to inhibit ice formation by use of high concentration of cryoprotectants and ultra-rapid cooling, but this is only successful across a limited number of biological objects and in small volume applications. This study explores physical processes of ice crystal formation in a model cryoprotective solution used previously in trials on vitrification of complex biological systems, to improve our understanding of the process and identify limiting biophysical factors. Here we present results of neutron scattering experiments which show that even if ice crystal formation has been suppressed during quench cooling, the water molecules, mobilised during warming, can crystallise as detectable ice. The crystallisation happens right after melting of the glass phase formed during quench cooling, whilst the sample is still transiting deep cryogenic temperatures. We also observe strong water isotope effects on ice crystallisation processes in the cryoprotectant mixture. In the neutron scattering experiment with a fully protiated water component, we observe ready crystallisation occurring just after the glass melting transition. On the contrary with a fully deuteriated water component, the process of crystallisation is either completely or substantially supressed. This behaviour might be explained by nuclear quantum effects in water. The strong isotope effect, observed here, may play an important role in development of new cryopreservation strategies.

Investigating the effect of holding duration at a deep cryogenic temperature on the wear behavior of DIN 1.2080 (D3) tool steel

This work focused on the effect of the holding time in a deep cryogenic heat treatment on the wear behavior, microstructural changes, retained austenite percentage and microhardness of 1.2080(D3) tool steel. These analyses were performed via optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and energy dispersion spectroscopy (EDS) to study the microstructure. A pin-on-disk wear testing machine was employed to investigate the wear behavior. The microhardness changes were measured by KOPA machine. It was shown that the deep cryogenic heat treatment eliminates retained austenite and makes a more uniform carbide distribution with higher percentages. Furthermore, some new nano-sized carbides form during the deep cryogenic treatment, thereby increasing the hardness and improving the wear behavior of the samples. It was also observed that the deep cryogenic heat treatment improves the wear behavior and microhardness of samples with an increase in the holding duration up to an optimum value: beyond that duration, the wear resistance and microhardness decreases to a specific value, and changed specifically at longer holding durations. It was also observed that the predominant wear mechanism was a combination of adhesive and tribochemical wear.

Effect of Deep Cryogenic Treatment on Wear Resistance of AISI 52100 Bearing Steel

In this study, the effects of deep cryogenic treatment (DCT) on the wear resistance of AISI 52100 bearing steel were investigated. For this purpose, a number of bearing steel samples were held for different times (12, 24, 36, 48, 60 h) at deep cryogenic temperatures (−145 °C). The wear experiments were carried out in a ball–disk arrangement, by applying loads of 10 and 20 N and a sliding velocity of 0.15 m/s. After conducting the experimental studies, 36 h was found to be the optimal holding time. At this holding time, the wear rate and friction coefficient were decreased, while the hardness reached to maximum values. It was observed that DCT led to significant microstructural changes, which resulted in improved tribological properties.

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and −196 °C

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (−196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at −196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled θ (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

Effects of Deep Cryogenic Treatment on Tribological Properties of the Tool Steel DC53

The bad quality of machining surfaces caused by the micro wear of pressing parts has been a very big trouble for the engineers over the past decades. In order to decrease the surface wear, the technology of heat treatment is used popular. Many papers about the heat treatment technology had been proposed. Especially, the deep cryogenic treatment has been used widely for the purpose of wear-resistance in the industry. Moreover, the method of using variations of surface magnetization to monitor the dynamic tribological properties between the metal pairs has been applied successfully by the author. Therefore, this paper is base on the above statements to further investigate the tribological properties of the tool steel by deep cryogenic treatment. It can be clarified for effects of different deep cryogenic treatment temperatures on wear-resistance of the tool steel DC53. Besides, the purpose of better quality and faster product speed of the pressing process can then be obtained.

Manufacture of Cryogenic Materials used in Automotive Industry

The paper presents the manufacturing of a cryogenic special S.G. cast iron used in automotive industry. The material used was a Mo-Cr-Ni S.G. cast iron, which it was elaborated in an induction furnace. Nodular changes were obtained with the “In mold” method, with the help of prealloy FeSiCuMg with 10-16% Mg, added into the reaction chamber in a proportion of 1.1% of the treated cast iron. After elaboration, it was made a heat treatment and then a maintaining on a low temperature (-70°C). Cryogenic treatment is methodology of ultra-low temperature processing of materials to enhance their properties to the desired levels. Material subjected to deep cryogenic temperature develops a more uniform, redefined microstructure with greater density. Austenite, the softer molecules in the microstructure is transformed to harder martensite. The experimental tests at low temperature (-70°C), were done in a specific cryogenic installation attached to an impact strength resistance tester. This installation used carbon dioxide solid like a cooling agent and ethylic alcohol as a cryogenic liquids. It is pointed out the influence of some factors (the temperature and the maintained time at the isothermal level and low temperature - 70°C) on the phase transformation and the KCV & KCU properties of the studied cast iron.

Internal Friction Study of the Influence of Deep Cryogenic Treatment on the Microstructure of a Bainitic Steel

The influence of deep cryogenic treatment (DCT) on the microstructure of a bainitic steel is investigated by means of internal friction and transmission electron microscopy (TEM). Two relaxation peaks (Pc1and Pc2) are observed during cooling and one relaxation peak (Ph) during heating from 100 to 320K. Peak Pc1may be related to dislocation pinning. Peak Phis attributed to dislocation-carbon atoms interaction. The decreasing of peak Phafter cycles deep cryogenic cooling indicates that soaking time under the deep cryogenic temperature is not contributed to the precipitation of carbides, while the cycles cryogenic treatment lead to more fine carbides precipitation.

Investigation on wear behaviour of cryogenically treated TiAlN coated tungsten carbide inserts in turning

Cryogenic treatment has been ascribed as a way of improving the cutting life of tungsten carbide turning inserts. Most of the research conducted till date has not reported any effort to excavate the effect of cryogenic treatment on the performance of coated tungsten carbide inserts in terms of adhesion strength of coatings deposited on tungsten carbide substrate. In order to understand the effect of cryogenic treatment on the adhesion strength of coatings, a comparative investigation of the wear behaviour and machining performance of cryogenically treated coated tungsten carbide inserts in orthogonal turning has been carried out in this study. The commercially available TiAlN coated square shaped tungsten carbide inserts (P25) were procured and subjected to cryogenic treatment at two levels −110 °C (shallow treatment) and −196 °C (deep treatment) of temperature independently. The criterion selected for determining the turning performance was based on the maximum flank wear (0.6 mm) as recommended in ISO 3685-1993. The results showed that shallow cryogenically treated coated tungsten carbide inserts performed significantly better as compared with deep cryogenically treated and untreated inserts. Major outcome of the present study includes a substantial decrease in tool life of deep cryogenically treated inserts as compared to untreated inserts indicating the destructive effect of deep cryogenic temperature (−196 °C) on TiAlN coated inserts which is further supported by VDI-3198 indentation test.

A 1k-pixel CTIA readout multiplexer for far-IR photodetector arrays

SB349 is the first 32 × 32 CTIA readout multiplexer specifically designed for far-IR photodetectors and is operable at cryogenic temperatures at least as low as 1.7 K. Four of these readouts can be butted together to form a 64 × 64 mosaic array. The array is multiplexed into eight parallel outputs and features eight selectable gain settings to accommodate various background levels, auto-zero for better input uniformity, and sample-and-hold circuitry. A special, 2-micron cryo-CMOS process was adopted to prevent freeze out and ensure low noise and proper operation at deep cryogenic temperatures. The read noise of the bare device at 4.2 K and under nominal sampling conditions was measured to be about 250e − for the 106fF signal capacitor with the well capacity of 400ke −. Hybridized to a typical germanium detector, the array should achieve NEP levels in the low 10 –18 W/√Hz. An overview of the design and the latest results of the test and characterization of this device are reported in this paper.

Influence of different cryotreatments on tribological behavior of 80CrMo12 5 cold work tool steel

This experimental study investigated the effect of cryogenic treatments on the wear behavior of 80CrMo12 5 tool steel. For this purpose, two different cryogenic temperatures were used: −80 °C as the shallow cryogenic temperature and −196 °C as the deep cryogenic temperature. The results showed that the cryogenic treatments decrease retained austenite, which is more effective in the case of the deep cryogenic treatment (DCT). As a result, a remarkable improvement in the wear resistance of the cryogenically treated specimens was observed. In addition, DCT increases the percentage of carbides and their homogeneity in distribution. An optimum holding time was found in the deep cryogenic temperature, in which the hardness and wear resistance show maximum values. Moreover, the wear debris and worn surfaces showed that the dominant mechanism in the wear test is adhesive.

On the Performance Limits of Cryogenically Operated SiGe HBTs and Its Relation to Scaling for Terahertz Speeds

The goal of achieving terahertz (THz) transistors within the silicon material system has generated significant recent interest. In this paper, we use operating temperature as an effective way of gaining a better understanding of the performance limits of SiGe HBTs and their ultimate capabilities for achieving THz speeds. Different approaches for vertical profile scaling and reduction of parasitics are addressed, and three prototype fourth-generation SiGe HBTs are compared and evaluated down to deep cryogenic temperatures, using both dc and ac measurements. A record peak f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> /f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of 463/618 GHz was achieved at 4.5 K using 130-nm lithography (309/343 GHz at 300 K), demonstrating the feasibility of reaching half-THz f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> and f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> simultaneously in a silicon-based transistor. The BV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CEO</sub> of this cooled SiGe HBT was 1.6 V at 4.5 K (BV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CBO</sub> = 5.6 V), yielding a record f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> times BV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CEO</sub> product of 750 GHzldrV (510 GHzldrV at 300 K). These remarkable levels of transistor performance and the associated interesting device physics observed at cryogenic temperatures in these devices provide important insights into further device scaling for THz speeds at room temperature. It is predicted in a new scaling roadmap that f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> /f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of room-temperature SiGe HBTs could potentially achieve 782/910 GHz at a BV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CEO</sub> of 1.1 V at the 32-nm lithographic node.

Effects of cryogenic treatment on wear behavior of D6 tool steel

In this paper, the effects of cryogenic treatment on the wear behavior of D6 tool steel were studied. For this purpose, two temperatures were used: −63 °C as shallow cryogenic temperature and −185 °C as deep cryogenic temperature. The effects of cryogenic temperature (Shallow and deep), cryogenic time (kept at cryogenic temperature for 20 and 40 h) and stabilization (kept at room temperature for 1 week) on the wear behavior of D6 tool steel were studied. Wear tests were performed using a pin-on-disk wear tester to which two different loads(120 and 180 N) and three different velocities (0.05, 0.1 and 0.2 m/s) were applied. The findings showed that the cryogenic treatment decreases the retained austenite and hence improves the wear resistance and hardness. Due to more homogenized carbide distribution as well as the elimination of the retained austenite, the deep cryogenic treatment demonstrated more improvement in wear resistance and hardness compared with the shallow cryogenic treatment. By increasing the keeping time at cryogenic temperatures, more retained austenite was transformed into martensite; thus, the wear resistance was improved and further hardness were observed. By keeping the samples for a period of 1 week at room temperature after quenching (stabilization), more retained austenite was transformed into martensite and higher wear resistance and higher hardness were achieved.

An Investigation of Negative Differential Resistance and Novel Collector–Current Kink Effects in SiGe HBTs Operating at Cryogenic Temperatures

In this paper, a new negative-differential-resistance (NDR) effect and a novel collector-current kink effect are investigated in the cryogenically operated SiGe heterojunction bipolar transistors (HBTs). Theory based on an enhanced positive-feedback mechanism associated with heterojunction barrier effect at deep cryogenic temperatures is proposed to explain both the observed NDR and the collector-current kink. The accumulated charge induced by the barrier effect acts at low temperatures to enhance the total collector-current, indirectly producing both phenomena. This theory is confirmed using the calibrated 2-D DESSIS simulations over temperature. These unique cryogenic effects also have significant impact on the ac performance of SiGe HBTs operating at high injection. Technology evolution plays an important role in determining the magnitude of the observed phenomena, and the scaling implications are addressed. In addition, the present NDR effect is also compared with previously reported NDR and hysteresis effects observed in highly scaled SiGe HBTs operating under forced-I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> -base bias. The input drive condition of the transistor during its use in circuits, either under pure forced-current bias or under pure forced-voltage bias, or more practically, somewhere in between, determines the magnitude of the observed NDR and is of potential concern for circuit designers and must be carefully modeled

A low noise 2 × 16 Ge:Sb focal-plane array: Paving the way for large format FPAs for far IR astronomy

Future astronomical instruments call for large format and high sensitivity far infrared focal-plane arrays to meet their science objectives. Arrays as large as 128 × 128 with sensitivities equal to or better than 10 −18 W/√Hz are set as targets for the far IR instruments to be developed within the next 10 years. These seemingly modest goals present a not-so-modest quantum leap for far IR detector technology whose progress is hampered by a number of complexities; chief among them the development of low noise readouts operating at deep cryogenic temperatures and a viable hybridization scheme suitable for far IR detectors. In an effort to incrementally develop large-format photoconductor arrays, we have fabricated a 2 × 16 Ge:Sb array using the SBRC190 readout – a cryogenic 1 × 32 CTIA readout multiplexer initially developed for SOFIA’s AIRES instrument. In this paper we report the results of the extensive parametric tests performed on this array showing an impressive noise performance of 2.2 × 10 −18 W/√Hz and a DQE of 0.41 despite some design limitations. With such an encouraging performance, this prototype array will serve as a platform for our future developmental effort.