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Characterization of NbSi TES Bolometers: Preliminary Results
Abstract
We present preliminary results on characterisation of voltage biased superconducting bolometers with an NbSi alloy sensor. I(V) curves as well as complex impedance and noise measurements are carried out in a dilution fridge with a pulse tube as a first stage cooler. SQUIDs polarization and addressing are controlled by a cold ASIC in which a SiGe amplifier has been implemented. First characterisations were done on full membrane bolometers and show a noise level of about
. Those detectors are developed for the QUBIC experiment, a B-modes telescope that will be deployed in Antactica in 2013.
... Unlike bilayer and multilayer sensors that are widespread among the TES community, we use an amorphous material combining controlled proportions of silicon and niobium. This technique has been investigated in the cryogenic detectors area for several years [6][7][8][9][10]. The Nb x Si 1−x can exhibit either insulating, metallic or superconducting properties depending mostly on niobium concentration. ...
As part of the Q&U Bolometric Interferometer for Cosmology instrument targeting the cosmic microwave background primordial B-modes, two kilo-pixel focal planes have been designed for a NEP of
W adapted for ground-based observations. Those pixels are transition edge sensors (TESs) made of voltage-biased NbSi thin films with a critical temperature
400 mK and TiV absorbing grids. The TESs are coupled to a time-domain multiplexed electronics based on superconducting quantum interference devices and an additional SiGe cryogenic integrated circuit which provides a second multiplexing stage. In this paper, we briefly discuss the instrumental context of a quarter of focal plane (a 256-TES sub-array). Then, we present its typical manufacturing process and first test results at cryogenic temperature.
... One kilo-pixel TES array is described as being made of 4 silicon wafers of 4 inches and 256 TESs each. TESs are based on NbSi thermistors [4][5][6][7] operating at 300 mK [8]. ...
A cryogenic 128:1 Time-Domain Multiplexer (TDM) has been developed for the readout of kilo-pixel Transition Edge Sensor (TES) arrays dedicated to the Q&U Bolometric Interferometer for Cosmology (QUBIC) instrument which aims to measure the B-mode polarization of the Cosmic Microwave Background. Superconducting QUantum Interference Devices (SQUIDs) are usually used to read out TESs. Moreover, SQUIDs are used to build TDM by biasing sequentially the SQUIDs connected together—one for each TES. In addition to this common technique which allows a typical 32 multiplexing factor, a cryogenic integrated circuit provides a 4:1 second multiplexing stage. This cryogenic integrated circuit is one of the original part of our TDM achieving an unprecedented 128 multiplexing factor. We present these two dimension TDM stages: topology of the SQUID multiplexer, operation of the cryogenic integrated circuit, and integration of the full system to read out a TES array dedicated to the QUBIC instrument. Flux-locked loop operation in multiplexed mode is also discussed.
... Le marché des MOEMS reste encore très fortement dominé par les applications d'affichage, mais de nombreux autres produits ont été fabriqués en séries plus réduites et beaucoup de démonstrateurs de laboratoire ont été développés. On peut par exemple citer : les micro-bolomètres [Martino 2012], les micro-miroirs adaptatifs [Fernandez 2003 ;Zamkotsian 2003], les modulateurs, commutateurs, filtres, atténuateurs, et sources ou détecteurs accordables pour les télécommunications [Wu 2006], les micro-capteurs et résonateurs avec actionnement ou/et détection optique [Graebner 2002 ;Hall 2008 ;Nieva 2009 ;Zhang 2007], les micro-instruments et micro-bancs optiques [Bargiel 2010 ;Lin 1994 ;Motamedi 1997], etc… Les MOEMS semblent pouvoir tout faire, mais il faut garder à l'esprit que leurs principales limitations sont inhérentes au procédé de fabrication. [Yamanoi 2008] Le choix des filtres Fabry Pérot est justifié par leurs propriétés optiques, mais il est nécessaire de bien analyser les avantages et les limitations des procédés de microfabrication pour sélectionner le procédé le mieux adapté : Premièrement, les procédés de microfabrication ne permettent souvent qu'une fabrication de structures 2D situées dans le plan du wafer, ceci rend donc difficile l'utilisation de miroirs verticaux. ...
Multispectral imaging is used to improve target detection and identification in monitoring applications. It consists in analyzing images of the same scene simultaneously recorded in several spectral bands owing to a filtering. This thesis investigates the possibility to realize, an array of four 3D integrated Fabry-Perot (FP) filters that are tunable in the visible-near infrared range by electrostatic actuation. The fixed mirrors of the FP filters are ZnS/YF₃ multilayers deposited on a borosilicate wafer, and the movable mirrors are PECVD SiNH/SiOH multilayer membranes clamped in a very compact movable structure micromachined in a Si wafer. A 3rd glass wafer is used for filters packaging. Optical performances of the FP filters have been optimized by taking into account the asymmetry and the reflection phase shift of the mirrors and the mobile structure has been modeled by finite elements analysis notably to minimize its deformation during actuation. The critical steps of the movable mirrors fabrication process in Si or SOI technology have been developed : i) the fabrication and the release by DRIE and XeF₂ etching of 8 or 12 layers membranes with a residual stress tunable by annealing and a reflectance close to 50% in broad wavelength range (570-900nm), ii) the control with temporary patterns of the simultaneous deep etching of patterns with different widths and depths, and iv) various patterning techniques on highly structured surfaces based on shadow masks (with mechanical alignment) or laminated photosensitive dry films. These results open the way towards the full realization of an array of 3D integrated FP filters.
We report on the performance of a superconducting NbSi transition edge sensor (TES), which is co-evaporated on a suspended SiO/SiN/SiO trilayer membrane. The temperature sensitivity coefficient (α) calculated from the measured resistive transition curve is as high as 200. The current-voltage characteristics were measured at bath temperatures varying from 288 mK to 440 mK using a two-stage SQUID amplifier, from which the thermal conductance (G) was found to be 345 pW/K. We also measured the current noise at different bias voltages at 288 mK. The obtained electrical noise equivalent power (NEP) from its calculated current responsivity and measured current noise is about 8 × 10-17 W/√Hz. In addition, the preliminary measurement results of time domain multiplexing scheme based on the superconducting quantum interference devices (SQUIDs) and an application specific integrated circuit (ASIC) are presented.
This paper presents an ultra low noise instrumentation based on cryogenic electronic integrated circuit. We have designed an ASIC (Application Specific Integrated Circuit) in standard BiCMOS SiGe 0.35 mum AMS technology. The main functions of this circuit, the readout and the control of a 24 to 1 SQUID multiplexer, is presented. We also report the cryogenic operation of each part of this ASIC.
The noise in superconducting transition-edge sensors (TESs) commonly exceeds simple theoretical predictions. The reason for this discrepancy is presently unexplained. We have measured the amplitude and frequency dependence of the noise in TES sensors with eight different geometries. In addition, we have measured the dependence of the noise on operating resistance, perpendicular magnetic field, and bath temperature. We find that the unexplained noise contribution is inversely correlated with the temperature width of the superconducting-to-normal transition and is reduced by a perpendicular field and in certain geometries. These results suggest paths to improved sensor performance. © 2004 American Institute of Physics.
We describe a method for measuring the complex impedance of transition-edge-sensor (TES) calorimeters. Using this technique, we measured the impedance of a Mo/Au superconducting transition-edge-sensor calorimeter. The impedance data are in good agreement with our linear calorimeter model. From these measurements, we obtained measurements of unprecedented accuracy of the heat capacity and the gradient of resistance with respect to temperature and current of a TES calorimeter throughout the phase transition. The measurements probe the internal state of the superconductor in the phase transition and are useful for characterizing the calorimeter. © 2004 American Institute of Physics.
We report on the superconducting properties of amorphous Nb
x
Si1−x
thin films. The normal-state resistance and critical temperatures can be separately adjusted to suit the desired application.
Notably, the relatively low electron–phonon coupling of these films makes them good candidates for an “all electron bolometer”
for Cosmological Microwave Background radiation detection. Moreover, this device can be made to suit both high and low impedance
readouts.
KeywordsTransition-edge sensors–Electron–phonon coupling–Superconductivity–Bolometer
The development of large superconducting
bolometer
(Transition Edge Sensor: TES) arrays requires ultra low noise amplification and multiplexing electronics. The use of a first transducer stage such as a SQUID
(Superconducting QUantum Interference Device) allows ultimate performance in terms of noise. However, the linearization of the SQUID characteristic requires low noise amplification. Furthermore, to realize a time domain multiplexer with SQUIDs, switched biasing is also needed. We have designed an Integrated Circuit (IC) in standard BiCMOS SiGe technology for the readout and the control of a SQUID
multiplexer. It includes a low noise amplifier with multiplexed inputs, switched current sources for SQUIDs, and digital circuit for the addressing with only one room temperature clock signal. We have successfully tested this integrated circuit down to 2 K. To validate the operation of a SQUID
multiplexer controlled by this SiGe cryogenic IC, we have developed a
2×2
SQUID hybrid demonstrator. It consists of four commercial SQUIDs connected to a SiGe IC.
- J N Ullom
Ullom, J.N. et al., Appl. Phys. Lett. 84, 4206 (2004)