Development of
Download
1 / 22

Development of TES-microcalorimeter arrays and Frequency Domain Multiplexed read-out Henk Hoevers - PowerPoint PPT Presentation


  • 118 Views
  • Uploaded on

Development of TES-microcalorimeter arrays and Frequency Domain Multiplexed read-out Henk Hoevers Division Sensor Research and Technology. Research Facilities for TES-microcalorimeter array and FDM development Two Kelvinox 100 dilution fridges 1 + 2 SQUID channels

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Development of TES-microcalorimeter arrays and Frequency Domain Multiplexed read-out Henk Hoevers' - maxim


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Development of

TES-microcalorimeter arrays

and

Frequency Domain Multiplexed read-out

Henk Hoevers

Division Sensor Research and Technology


  • Research Facilities for TES-microcalorimeter array and FDM development

  • Two Kelvinox 100 dilution fridges

    • 1 + 2 SQUID channels

    • moveable slit to position X-ray beam (micron resolution)

    • data-acquisition facilities: RT-, IV-curves, analog and digital pulse processing

    • X-ray sources: 5.9 keV and 1.5/2.2/3.0/3.3/5.9 keV

  • In-house clean room -> short turn-around times for detector research

    • class 10-100

    • processing on 4” wafers, sputter deposition, thermal evaporation,

    • spinners, mask aligners, wire bonders, inspection equipment

  • Staff

    • Physicists: 6 fte (senior) scientists

    • Electronics: 2.5 fte (senior) design engineers

    • Support staff: 2.5 fte (mechanical, electronical, lab assistant)

    • Clean room staff: 3 full-time persons


  • Funding of TES-microcalorimeter array and FDM development development

  • SRON staff from NWO income (Dutch Organization for Scientific Research)

  • ESA TRP contract ‘Cryogenic Imaging Spectrometer’ (XEUS – NFI2)

  • SRON

  • TES-based arrays (thin film processing, testing), prime contractor

  • MESA+, Twente University, the Netherlands

  • micromachining development

  • VTT Automation Technology, Espoo, Finland

  • SQUID development

  • Space Research Center, Leicester, UK

  • detector packaging, pulse processing

  • University of Jyvaskyla, Finland

  • material parameters at sub-Kelvin temperatures

  • Metorex, Espoo, Finland

    • electrical crosstalk simulations (dense wiring)

  • SRON and partners will tender on X-10 (expected ESA TRP on array read-out)


Set-up of the talk development

TES microcalorimeter array development

Status of Frequency Domain Multiplexing

Outlook area: energy resolution


  • Microcalorimeter array development for XEUS; approach development

  • development of 5 x 5 pixel array with XEUS specification

  • address/investigate scalability from 5 x 5 array to 32 x 32 array

  • Production: fabrication of prototype 5 x 5 arrays following two routes

  • bulk micromachining

  • surface micromachining

  • Performance characterization of 5 x 5 pixel arrays

  • R(T), I(V) curves and their reproducibility

  • noise and energy resolution

  • Detector (re)design (5 x 5 -> 32 x 32) uses

  • performance (and understanding) of 5 x 5 arrays

  • additional measurements of all relevant low-temperature material parameters

  • development of a Finite Element Model of the 5 x 5 array (thermal design)

  • The Finite Element Model is also suited for performance analysis (time dependent

  • pulse modeling) and investigation of other pixel sizes and/or geometries


240 development μm

Bulk and surface micromachining (SRON-MESA); the 5 x 5 arrays

TiAu TES (100 mK)

and Cu absorber

on slotted

SiN membrane


R development (T) and I(V) curves

Bulk MM

Three pixels

in the same array

Bulk MM

Three pixels

in different arrays/chips

Surface MM

Three pixels

in the same array


  • Bulk micromachining; pulse performance/energy resolution development

  • Effective time constant: τeff = 300 to 400 μs

  • This is 3 - 4 times lower than expected (and what was designed for)

  • Thermal conductance of SiN/Si(110) is 3 - 4 times lower than of SiN/Si(100)

  • Measured energy resolution ∆E = 6 - 7 eV at 6 keV

  • Resolution not understood; from the measured noise 4 - 5 eV is expected

  • Note: the best single pixels have ∆E = 3.9 eV and τeff = 85 μs


In progress: Bi-absorber arrays (7 development μm thick with Cu bottom/thermalisation layer)

Mushroom shaped absorbers: thermal evaporation and lift-off

Problems encountered for XEUS sized pixels (240 x 240 μm2) in 5 x 5 arrays:

lift-off edges, particle-like anomalies, μ-cracks in Bi

Single pixel

Bi-absorber

Hat: 160 x 160 μm2

Stem: 100 x 100 μm2

5 x 5 array

Bi absorbers

Hat: 240 x 240 μm2

Stem: 100 x 100 μm2


Material parameters and Finite Element Modeling development

5 x 5 pixel array

32 x 32 pixel array

Advanced detector design through Finite Element Modelling (2D, 3D)

  • Measured and modelled thermal transport

  • el-ph coupling in TES and absorber

  • Kapitza coupling between TES - SiN

  • conductance silicon nitride membranes

  • conductance Si support beams

  • thermal coupling of Si chip to heat bath

Basic layout of a sensor pixel


SiN development

Si-beam with Cu

SiN

Uncoated Si

Si-beam

Beam with Cu

side view Si(110) beam

Finite Element Model of the XEUS array (1000 pixels of 10 pW each)

  • Thermal coupling of detector pixels to heat bath

  • Bare Si chip Tchip = 187 mK TSi beam = 200 mK

  • Cu coating back-side Si-chip Tchip = 41 mK TSi beam = 140 mK

  • Cu coating on Si beams and chip Tchip = 41 mK TSi beam = 47 mK

Improvement of coupling chip to bath

!

Improvement of coupling to heat bath and a small thermal gradient in Si beam: proper heat bath

Future XEUS 32 x 32 pixel array


  • Array development - summary development

  • Array production based on bulk and surface micromachining

  • The pixel to pixel performance in BMM and SMM arrays is quite good (R(T), I(V))

  • Thermal conductance of SiN on Si(110) is lower than expected -> τeff too high

  • To be measured: pixels with redesigned thermal support

  • Improvement of ΔE from 6 - 7 eV to values smaller than 5 eV needed

  • Working on reduced sensitivity of set-up for EMI

  • Working on more fundamental issues of the energy resolution

  • Development of large mushroom-shaped absorbers is critical and has high priority

  • The XEUS detector chip and pixels can be adequately cooled

  • Detailed Finite Element Model is available for thermal design, all relevant

  • low-temperature material parameters measured


  • Frequency Domain Multiplexing - Motivation for multiplexed read-out

  • Thermal aspects related to the read-out and biasing of one pixel

  • Power dissipation: 10 pW/pixel

  • Power dissipation; 100pW/shunt resistor

  • Power dissipation: 1 nW/SQUID current amplifier

  • Heat input through wiring (5 at minimum, 4 twisted-wire pairs preferred)

  • Available cooling power XEUS ADR: 5.5 μWh @ 35 mK

  • 32 x 32 pixel array without multiplexing: only ~4 hours of operation!



  • Need for loop gain read-out

  • Large dynamic range required (current pulse vs current noise)

  • DR = 8.106 = Φ0/(2ΦSQUID) (1+LFLL); low-noise VTT SQUID: LFLL > 1.4

  • Common impedance (SQUID input coil) leads to cross talk (from f1 to f2)

    • CT = 0.001 = [Lc/(1+LFLL )/L]2; LFLL > 10

  • The SQUID is an non-linear component -> mixing products (from f1 to f2)

  • CT = 0.001 requires LFLL > 15


    • Limitations of the achievable loop gain read-out

    • Phase rotation due to cable delay imposes: tdelay.foperation < 0.11/LF;

    • For an optimized cryostat with 20 cm distance between SQUID and

    • warm electronics (t delay = 3 ns)

    • Phase rotation of the amplifier (simulation performed for a 200 MHz amplifier with one pole zero compensation)

    • Standard FLL

    • Combining 32 channels (with 100 kHz seperation) requires 3 MHz

    • LFLL~ 10 @ 3 MHz

    • It requires very close packing and the available low loop gain is low; it implies an appreciable fraction of mixing products

    • Baseband feedback

    • The carrier is deterministic and carries no information (use it in the feedback)

    • In principle, only the signal bandwidth (200 kHz) is relevant; it allows for high loop gains

    • LFLL ~ 200 @ 200 kHz


    Standard FLL read-out

    Pro: Con:

    FLL proven concept- A-linearity in SQUID introduces crosstalk at 0.2% level

    - Common impedance leads to crosstalk at 0.4% level

    - Bandwidth limited to ~3 MHz, 32 close packed channels


    Baseband feedback read-out

    • Pro: Con:

    • L > 200 results in: Complex demux/mux electronics

    • A-linearity in SQUID: crosstalk at < 0.01% level

    • Idle-current cancellation not required

    • Available bandwidth is up to ~10 MHz; allows for well-spaced carriers ->

    • cross-talk due to common impedance is no longer a problem


    Experimental status Frequency Domain Multiplexing (biasing of detectors)

    Biasing of microcalorimeter

    AC-bias measurements at 500 kHz to study potential switch-off behavior

    Microcalorimeter can be biased over the whole transition provided that the there is a small impedance in the biasing circuit <-> low dielectric loss in C

    Set-up for 250 kHz FLL operational and optimized

    Electronic resolution of FLL electronics, bias sources and mixers/de-mixers, and SQUID for detector biased in normal state is at present 2 eV

    Tests with a TES microcalorimeter with 5 eV resolution @ 6 keV (DC)

    AC-bias experiment at 50 kHz with 6.5 eV @ 6 keV

    Baseline noise 5 eV (~sensor dominated resolution)

    AC-bias experiment at 500 kHz with 8.8 eV @ 6 keV

    SQUID back-action noise (LSQUID) limits resolution of 8-9 eV

    AC-bias experiment at 250 kHz with 7 eV @ 6 keV

    Baseline noise 5 - 6 eV (sensor dominated resolution)


    Status Frequency Domain Multiplexing (noise blocking filters)

    LC filters required with Q ~2500 (depends on carrier frequency)

    Washer-type superconducting coils

    Minimize dimensions (reduce intercoil cross-talk)

    Superconducting capacitors

    High dielectric constant (small components)

    Low dielectric losses (tan δ < 0.001; introduces resistance)

    Si3N4 (VTT): Q = 2800 (compatibility of Si3N4 process)

    Al2O3 (SRON): Q = 300 (limited by critical current)

    L = 100 nH

    500 m

    Test structures: 2.4 to 240 nF; size up to 4 x 4 mm2

    Low leakage, R ~ 1 mΩ


    • Outlook area: energy resolution filters)

    • ΔE = 2.35 ξ [kBT2C]1/2

    • Microcalorimeter physics Low heat capacity absorbers

    • What motivates the improvement of ΔE?

    • there is still very limited margin on ΔE with respect to the specification

    • for XEUS and other applications

    • the development of large area pixels with a good ΔE requires

    • that ξ and/or C are as low as possible (and under control)


    • Outlook – summary filters)

    • Detector physics – improvement of energy resolution (design: 1 – 1.5 eV)

    • Typical energy resolution (measured) 4 - 5 eV

    • Possible improvement pulse filtering factor 1.5 – 2 (Fixsen method)

    • Possible improvement by ITFN reduction factor 1.5 – 2 (TES with lower RN)

    • Device testing (single pixels and arrays)

    • Large area pixels

    • Low C materials: Bi, Sn

    • Compatibility with large arrays?

    • Design optimization, thermalization issues: ΔE and ΔE_xy (position dependence)

    • Production

    • Device testing (single pixels and arrays), E < 6 keV

    Absorber development


    ad