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Feasibility of 4H-SiC p-i-n Diode for Sensitive Temperature Measurements between 20.5 K and 802 K
摘要： For the first time, we report on the performances of 4H-SiC pin-diode temperature sensors for operating temperatures between 20.5 K and 802 K. In this huge temperature range three ranges of performance were identified with the limit temperatures at 78.2 K and 176.3 K. In each of these ranges a different dominant current transport mechanism is shown and in the manuscript a detailed analysis and discussion is reported. The sensor performances were extracted from VD-T characteristics at different fixed ID values. In particular, at ID=1 μA and in the temperature range between 78.2 K and 802 K, we found a sensor sensitivity of 2.3 mV/K up to 3.4 mV/K with a rms temperature error, eT, of less than 4.2 K and the sensor shows an excellent linearity – quantified by the coefficient of determination R2 higher than 0.9993. For even lower temperatures (below 78.2 K), low measurement currents like 10 nA are required leading to a sensitivity of 5.8 mV/K, but a lower linearity (R2=0.9095) and a rms temperature error of 9.7 K which makes the sensor only partially usable in the temperature range between 20.5 K and 78.2 K. Finally, the sensor performances are compared to other state-of-the-art solutions.
关键词： Semiconductor device modelling,Cryogenic temperatures,Temperature sensors,4H-Silicon Carbide device,High temperatures,Semiconductor p-i-n diodes
更新于2025-09-23 15:22:29
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Occurrence control of charged exciton for a single CdSe quantum dot at cryogenic temperatures on an optical nanofiber
摘要： We discuss photo-luminescence characteristics of CdSe core/shell quantum dots at cryogenic temperatures using a hybrid system of a single quantum dot and an optical nanofiber. The key point is to control the emission species of quantum dot to charged excitons, known as trions, which have superior characteristics to neutral excitons. We investigate the photocharging behavior for the quantum dots by varying the wavelength and intensity of irradiating laser light, and establish a method to create a permanently charged situation which lasts as long as the cryogenic temperature is maintained. The present photo-charging method may open a new route to applying the CdSe quantum dots in quantum photonics, and the hybrid system of photocharged quantum-dot and optical nanofiber may readily be applicable to a fiber-in-line single-photon generator.
关键词： Optical nanofiber,Cryogenic temperatures,CdSe quantum dots,Photocharging,Trions
更新于2025-09-23 15:21:01
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High-Quality Reduced Graphene Oxide Electrodes for Sub-Kelvin Studies of Molecular Monolayer Junctions
摘要： Electron transport phenomena in molecular monolayers are complex and potentially different from those for example, molecule?molecule interactions. Unfortunately, access to detailed mechanistic investigations of molecular monolayer junctions at ultralow temperatures is typically hampered by the narrow range of operating temperatures for most large-area device platforms. Here, we present a highly optimized chemically derived graphene material with a near temperature-independent conductance profile. Using this material as a conducting interlayer electrode in solid-state molecular electronic devices, we show robust and reliable large-area molecular junction operation at temperatures ranging from room temperature to below 1 K, and we demonstrate the ability to measure inelastic electron tunneling spectroscopy of a conjugated molecular monolayer at cryogenic temperatures.
关键词： inelastic electron tunneling spectroscopy,cryogenic temperatures,molecular monolayers,graphene,electron transport
更新于2025-09-23 15:21:01
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Silicon nitride and silica quarter-wave stacks for low-thermal-noise mirror coatings
摘要： This study investigates a multilayer high reflector with new coating materials for next-generation laser interferometer gravitational wave detectors operated at cryogenic temperatures. We use the plasma-enhanced chemical vapor deposition method to deposit amorphous silicon nitride and silica quarter-wave high-reflector stacks and studied the properties pertinent to the coating thermal noise. Room- and cryogenic-temperature mechanical loss angles of the silicon nitride and silica quarter-wave bilayers are measured using the cantilever ring-down method. We show, for the first time, that the bulk and shear loss angles of the coatings can be obtained from the cantilever ring-down measurement, and we use the bulk and shear losses to calculate the coating thermal noise of silicon nitride and silica high-reflector coatings. The mechanical loss angle of the silicon nitride and silica bilayer is dispersive with a linear weakly positive frequency dependence, and, hence, the coating thermal noise of the high reflectors show a weakly positive frequency dependence in addition to the normal 1/sqrt(f) dependence. The coating thermal noise of the silicon nitride and silica high-reflector stack is compared to the lower limit of the coating thermal noise of the end test mirrors of ET-LF, KAGRA, LIGO Voyager, and the directly measured coating thermal noise of the current coatings of Advanced LIGO. The optical absorption of the silicon nitride and silica high reflector at 1550 nm is 45.9 ppm. Using a multimaterial system composed of seven pairs of ion-beam-sputter deposited Ti:Ta2O5 and silica and nine pairs of silicon nitride and silica on a silicon substrate, the optical absorption can be reduced to 2 ppm, which meets the specification of LIGO Voyager.
关键词： quarter-wave stacks,silica,silicon nitride,gravitational wave detectors,thermal noise,mechanical loss,cryogenic temperatures,optical absorption,mirror coatings
更新于2025-09-19 17:15:36
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Spectroscopy and diode-pumped continuous-wave laser operation of Tm:Y2O3 transparent ceramic at cryogenic temperatures
摘要： We present the spectroscopic and laser characteristics of a 3 at.% Tm:Y2O3 transparent ceramic at cryogenic temperatures. An absorption cross section of 4.7 × 10?21 cm2 with a bandwidth of 0.7 nm centered at 793.3 nm and an emission cross section of 29.0 × 10?21 cm2 centered at 1930.9 nm were estimated at 80 K. Continuous-wave laser operation was achieved using broadband and VBG stabilized laser diodes emitting around 793 nm as pump sources. With the VBG pump diode, a maximum output power of 6.4 W was achieved at 80 K corresponding to a slope efficiency of 52.0% with respect to absorbed power.
关键词： cryogenic temperatures,diode-pumped,Tm:Y2O3,spectroscopy,continuous-wave laser,transparent ceramic
更新于2025-09-19 17:13:59
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The $$\hbox {Na}_2\hbox {W}_2\hbox {O}_7$$Na2W2O7 crystal: a crystal scintillator for dark matter search experiment
摘要： A single crystal of Na2W2O7 (NWO) was grown by a low-thermal-gradient Czochralski technique (LTG-CZ). The scintillation properties of the crystal were evaluated for the ?rst time as a potential material for dark matter search experiments. The luminescence and scintillation characteristics of the crystal were studied at room temperature and low temperatures by using a light-emitting diode (LED) and a 90Sr beta source. The luminescence and scintillation light yield at 10 K were signi?cantly higher than those at room temperature. The crystal showed higher light yield at 10 K than a CaMoO4 (CMO) crystal. The decay time of the crystal was investigated at temperatures between 10 and 300 K. The sensitivity to spin-independent weakly interacting massive particle-nucleon interactions based on 10 kg (2 months) and 50 kg (12 months) data for the NWO crystal detectors was estimated by a simulated experiment using the standard halo model. The luminescence, scintillation, and sensitivity results revealed that the NWO crystal is a promising candidate for a dark matter search experiment in the near future.
关键词： dark matter search,Na2W2O7 crystal,cryogenic temperatures,luminescence,scintillation properties
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Spin-Dependent Transport of Charge Carriers in Silicon Microcrystals Doped with Boron and Diluted with Nickel
摘要： Negative magnetoresistance of Si p-type whiskers with different impurity concentration 1018 – 5×1018 (cid:619)m-3 which corresponds to the transition of a metal-dielectric in silicon and diluted with nickel were studied in longitudinal magnetic field 0 – 14 T in the temperature range 4.2 – 77 K. The large negative magnetoresistance values correspond to hopping conductance on the twice occupied by electrons impurity states. It is established that in order to predict the magnetoresistance of crystals, it is necessary to take into account the polarization component due to the nature of the hopping conductance at low temperatures
关键词： negative magnetoresistance,spin,whiskers,hopping conductance,cryogenic temperatures
更新于2025-09-04 15:30:14