Substrates Used for Cryogenic Research
A US National Lab requested a quote for the following:
We are looking to purchase n-type Gallium Arsenide doped with silicon and boron for an experiment where we will using the crystals as cryogenic scintillators and coupling the light output into superconducting nanowire single photon detectors.
We need 1 x 1 x 0.5 mm samples for our first set of experiments. It looks like you have a variety of options in stock that might work.
Can you confirm what you have in stock now that would fit these specifications with a high dopant concentration? I am also wondering what the lead times are and whether you could cut up a wafer to fit the dimensions I referenced above.
Reference #260307 for specs and pricing.
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Sapphire for Cryogenic Design
A research associate requested the following quote:
As we are working on cryogenic design. Could you please provide thermal behavior and data file for the sapphire substrate so that we can simulate and use in the fabrication. I look forward for your reply.
UniversityWafer, Inc. Quoted:
Pls see below for all the property of the sapphire wafer" Dielectric properties and optical properties :
Sr. No. Property Value
- Material 99.996% pure Al2O3 (Alumina)
- Material class according to DIN EN 60672 C795
- Density 3.73 g/cc
- Coefficient of thermal expansion
100° – 200° C 6.0 – 8.0 * 10 -6 /K
100° – 300° C 6.0 – 8.0 * 10 -6 /K
100° – 600° C 6.7 – 8.7 * 10 -6 /K
100° – 800° C 7.0 – 9.0 * 10 -6 /K
- Dielectric constant (10 MHz to 1 GHz) 8.3 – 11.3
- Dielectric loss factor (10 MHz to 1 GHz) ≤ 5 * 10 -3
- Breakdown field ≥ 15 kV/mm
- E-Modulus ≥ 300 GPa
- Thermal conductivity at 20° C ≥ 22 W/m K
- Volume resistivity at
20° C ≥1013 Ω-cm
200° C ≥1011 Ω-cm
400° C ≥109 Ω-cm
600° C ≥107 Ω-cm
- Water absorption ≤ 0.1%
- Light transmission characteristics: T>/=80% (0.3～5μm) Refractive index: no =1.768 ne =1.760
Reference #261017 for specs and pricing.
Development of ultra-stable cryogenic sapphire oscillators (CSOs) with low-vibration cryocoolers and custom cryostats has delivered unprecedented performance [2] [4] in a low-maintenance package accompanied by the need to generate user frequency (RF) and millimeter (X-band) signals with low degradation of signal quality. The cryogenic Sapphire Oscillator (CSO) is a stable source of microwave signals with a short integration time that provides stability in parts of 10-16 1 / s and 5x103 / s and no drifting 5x10-15 1 / day. Sapphire crystals are an ultra-stable frequency reference that shows no significant drift after a day of integration. [Sources: 5, 8]
Cryogenic Wafers Used in Cryogenic Design
The process of cryogenic design begins with the fabrication of the wafers. This process produces ultra-thin, 
high-quality crystalline silicon in a variety of different thicknesses. The wafers are then cooled using liquid cryogens to achieve a high level of purity and accuracy. The entire system is pre-cooled with liquid nitrogen, purged with liquid helium, and switched over to a low-temperature environment. During the cooling process, a binary gas analyzer monitors the exhaust to ensure a low-temperature environment.
This process is widely used in semiconductor manufacturing. The niobium layers are used to produce ultra-thin silicon. This type of wafers is highly conductive, which is essential for modern electronics. This type of wafers is highly sensitive and can detect a variety of physical phenomena. The cryogenic environment is also used to produce sensors for a variety of applications, including industrial materials analysis, military systems, concealed weapons detection, and astronomy.
The first step is to prepare the wafers for cryogenic testing. A specialized probe station is used to remove flux and measure fast rise-time electrical signals. The probe station must operate at near-four-kelvin temperature to minimize liquid helium losses. This is a common process for conducting measurements in acoustic astrophysics experiment. These experiments are the first to use this technology.
The process is highly complicated and requires specialized equipment to complete. The wafers are cooled in the most precise and accurate manner possible. This method can be compared directly with chip-level testing in liquid helium. The method is highly sensitive and offers valuable information for process engineers. It is also an ideal technique for developing superconducting components. The process can be performed in a range of temperatures and has many applications in high-end electronics.
In addition to the probe station, a cryogenic wafer prober is an instrument that uses a probe head mounted on a nonmagnetic x-y stage. The test site is typically 22x22 mm(2) in size. A repeatability of 1 microm is possible using this process. The tester is also required to check the wafers in liquid helium for a specific temperature.
To make a cryogenic processor, it is necessary to use a memory system. This means that a device must be very cold. While superconducting memory is still years away, traditional CMOS DRAM structures can be effectively used at cryogenic temperatures. The process is complicated, but the advantages are significant. The device can be manufactured without any additional equipment. In addition to this, it requires a special probe card.
The process of cryogenic design uses high-quality cryogenic wafers. The technology is very efficient and can reduce production costs. The process of cryogenic design involves modifying the probe card. The probe card allows for the processing of a single wafer. Once the probe card is modified, it can handle a large number of wafers simultaneously. Using a dedicated machine for this purpose is essential for a quality device.
This method of cryogenic design is highly beneficial for the semiconductor industry. In addition to reducing costs, it also enhances product quality. By utilizing the probe card, the process is able to produce a wide variety of products. It is also a more convenient way to exchange wafers. A new probe card allows the process to take place at a higher speed and reduce the risk of damage.
For the process of cryogenic design, the wafers must be properly prepared before the process is conducted. The cooled wafers need to be prepared before the actual process. The cooled wafers are required for the RF tests. Using this technology can make the wafers very reliable. The temperature of the device is also the limiting factor. The probes should be placed in the same location for maximum quality.
The probe should measure the critical current of the wafer. The resistance to the junction should be a constant voltage. Usually, the resistance between the wafer and the probe is equal to the temperature of the probe. However, the temperature of the junctions depends on the size of the chip. The smallest of the two is 500 nm, and it has an energy gap of 50 nW.
Cryogenic Design Research
This research examined the effects of thermal circulation in a room at cryogenic temperatures between 300K and 4K on thermal expansion coefficients of two ceramic substrates: silicon nitride (Si3N4) and alpha alumina (sapphire) (Al2O3). We also reported on the reduction of thermal lenses in cryogenic sapphire mirror planes using the large-scale cryogenic gravity wave telescope project (LCGT). [Sources: 0, 2]
We measure three key parameters of the sapphire substrate: thermal lens and cryogenic temperature. These parameters are the optical absorption coefficient, the thermal conductivity, the temperature coefficient and the refractive index at cryogenic temperatures. [Sources: 0]
Based on these measurements, we estimated the shot sensitivity of interferometer thermal lenses using wavefront simulations. White CSI samples were used and optical absorption measurements were performed. [Sources: 0]
The signal degradation at 100 MHz was estimated at less than 10 MHz due to the self-noise in the frequency divider component used. The performance of T = 10.3 s was superior to previous results. One of the frozen sapphire oscillators was built with the same spiral crystal four times after the measurements, but one of the thermal stabilization features with passive thermal filtering was not implemented. [Sources: 8]
Chapter 4 examines the influence of crystal orientation on the tensile strength of hydroxide catalysis bonds in sapphire. In this paper we report on the results of two samples of sapphire obtained from boules grown using a modified Kyropoulos method by melting raw material in a crucible and putting the seeds in contact with a bath in which the temperature is lowered to control the way the crystals grow in the bath. [Sources: 6, 9]
The focused beam is modulated by the optical chopper with a fixed frequency and the temperature changes are modulated linearly. The power absorbed by our sample is low and the amplitude of temperature modulation is proportional to its local absorption coefficient. It should be noted that the absorption coefficient contains secondary contributions, such as thermal loads mediated by changes in the refractive index. [Sources: 9]
Knowledge of fluorescence cross sections and line shapes at cryogenic temperatures is of crucial importance to the designer of CPA laser systems to model the amplification process and performance of the laser system. [Sources: 1]
Section 2 describes measurements of the fluorescence spectrum at temperatures from 77K to 300K. Section 3 presents calculations of the amplification cross-section and the line shape as well as corresponding fit parameters, which are used for modelling the CPA gain. Section 4 presents simulations of multipass amplifiers with the amplification and line shapes presented in Section 3 at cryogenic and room temperatures. [Sources: 1]
The two most promising candidates for cryogenic mirrors with suspension elements are sapphire and silicon. A cryogenic detector, the Japan-based Karag Observatory, is under construction and uses sapphires as material for its mirror suspension elements. [Sources: 6]
One such area of further development is the pair operation of detectors at cryogenic temperatures where improvements in mirror and suspension design are aimed at increasing sensitivity and reducing thermal noise effects. Due to its unfavourable thermomechanical properties, quartz glass used as a mirror surface, suspension fiber and elements for detectors at room temperature can't be used in cryogenic temperature detectors. Changes in mirrors, substrates and suspension materials are therefore necessary for the construction of cryogenic detectors. [Sources: 6]
This paper examines the latest developments in high-performance gyrotronoscillators for fusion plasma and industrial applications. The purpose of this section is to show that significant changes in the amplified laser spectra can be used for cryogenic cooling. Gyrotron oscillators can also be used for material processing. [Sources: 1, 4]
For the 100-TW laser system used in this case study [8,27] there are two multi-pass amplifier stages based simulations on a 3D amplification model [27]. With the Jaeri FZK-GYCOM an overall efficiency of 50-60% was achieved using a single-stage depressive collector (SDC). [Sources: 1, 4]
The additional surveillance power is particularly important in the defence context and provides additional intelligence. Sapphire watches are the culmination of 20 years of cutting-edge research that has shown the world how to beat laboratory performance. In response to the call for better radar signals, the Sapphire team began working with the High Frequency Radar Team (DST) to research the JORN project. [Sources: 3]
How to Fabricate Cryogenic Sapphire Oscillators: An Overview
Cryogenic sapphire oscillators, also known as cryogenic sapphire resonators, have garnered significant attention in recent years for their exceptional frequency stability, low noise, and precise timekeeping abilities. These characteristics make them ideal for various applications, including atomic clocks, deep space communication, radar systems, and radio astronomy. In this article, we will discuss the fabrication process of cryogenic sapphire oscillators and their applications in different fields.
Sapphire Material:
The core component of a cryogenic sapphire oscillator is the sapphire crystal. Synthetic sapphire (Al2O3) is used due to its desirable characteristics such as high thermal conductivity, low thermal expansion, and excellent mechanical and chemical stability. Sapphire crystals are grown using methods like the Kyropoulos, Czochralski, or edge-defined film-fed growth (EFG) techniques. The final product is a single crystal sapphire, which serves as the base material for the oscillator.
Shaping the Sapphire:
The single crystal sapphire is cut into a cylindrical shape known as a Whispering Gallery Mode (WGM) resonator. This is achieved using a combination of techniques, including diamond sawing, grinding, and polishing. The final dimensions and surface finish of the cylinder are crucial, as they directly impact the resonator's quality factor (Q), which is a measure of the oscillator's stability and performance.
Cryogenic Mounting: To achieve the desired frequency stability, the sapphire resonator must be cooled to cryogenic temperatures, typically around 4-10 K. The resonator is mounted within a cryostat, which is a vacuum-insulated container designed to maintain ultra-low temperatures. The mounting process must account for thermal contraction and ensure that the sapphire crystal remains stress-free, as mechanical stress can degrade the oscillator's performance.
Coupling Mechanism: For the sapphire resonator to function as an oscillator, an external excitation source is needed. This is typically achieved using a microwave signal generator coupled to the resonator using a loop antenna or dielectric resonator. The coupling strength must be optimized to ensure efficient energy transfer between the resonator and the microwave source, thereby maximizing the Q factor and overall oscillator performance.
Electronics and Control System: A phase-locked loop (PLL) control system is utilized to maintain the oscillator's frequency stability. The PLL system compares the output frequency of the sapphire resonator with a reference frequency and generates an error signal. This error signal is then used to control the microwave source's frequency, locking it to the desired frequency of the sapphire resonator.
Final Assembly and Testing: Once all components are assembled, the cryogenic sapphire oscillator undergoes thorough testing to ensure optimal performance. Measurements of the Q factor, frequency stability, and phase noise are performed to characterize the oscillator's performance. These tests also serve as a benchmark for future performance assessments and maintenance.
Applications of Cryogenic Sapphire Oscillators:
- Atomic clocks: Due to their exceptional frequency stability, cryogenic sapphire oscillators have been used in atomic clocks, which are critical for global positioning systems (GPS), telecommunications, and scientific research.
- Deep space communication: Cryogenic sapphire oscillators enable precise timekeeping and low phase noise, making them ideal for deep space communication systems where signal integrity is paramount.
- Radar systems: High-performance radar systems rely on stable oscillators for accurate target detection and tracking. Cryogenic sapphire oscillators offer improved performance compared to traditional quartz-based oscillators.
- Radio astronomy: In radio astronomy, cryogenic sapphire oscillators provide a stable reference frequency for radio telescopes, allowing for accurate observations of celestial objects and phenomena.
In conclusion, the fabrication of cryogenic sapphire oscillators is a complex process involving the growth of synthetic sapphire crystals, precise shaping and polishing, cryogenic mounting, and the implementation of coupling mechanisms and control systems. The exceptional frequency stability, low noise, and precise timekeeping capabilities of these oscillators have made them invaluable in various applications, including atomic clocks, deep space communication, radar systems, and radio astronomy. As technology continues to advance, it is likely that cryogenic sapphire oscillators will play an increasingly important role in the development of next-generation timekeeping, communication, and observation systems.
In conclusion, the fabrication of cryogenic sapphire oscillators is a complex process involving the growth of synthetic sapphire crystals, precise shaping and polishing, cryogenic mounting, and the implementation of coupling mechanisms and control systems. The exceptional frequency stability, low noise, and precise timekeeping capabilities of these oscillators have made them invaluable in various applications, including atomic clocks, deep space communication, radar systems, and radio astronomy. As technology continues to advance, it is likely that cryogenic sapphire oscillators will play an increasingly important role in the development of next-generation timekeeping, communication, and observation systems.
