tunnel junction refrigerators cooling from 300 mk to 112 mk with large cooling power
DESCRIPTION
Tunnel Junction Refrigerators Cooling From 300 mK to 112 mK with Large Cooling Power. Galen O'Neil For Peter Lowell (his knee ). NIST Boulder NIS Team Peter Lowell Dan Schmidt Jason Underwood Joel Ullom. NIS Refrigerator. hot. (Al-Mn)Ox. Al. Al. I. Substrate (Si). cold. Al-Mn. - PowerPoint PPT PresentationTRANSCRIPT
Tunnel Junction Refrigerators Cooling From 300 mK to 112 mKwith Large Cooling Power
Galen O'NeilFor Peter Lowell(his knee )
NIST Boulder NIS TeamPeter LowellDan Schmidt
Jason UnderwoodJoel Ullom
NIS Refrigerator
Si
Al-MnAl-MnSiO2
AlAl(Al-Mn)Ox
Superconductor(Al)
Normal Metal (AlMn)
Junc
tion
Substrate (Si)
10 um
I
I
hot
hothot
hot
hot
cold
cold
More options for refrigeration below 300 mK
Dilution refrigeratorMost expensive10 mK
2-stage 3He
ADRModerate price50 mK
NIS refrigerator cooling detectors 100 mK
cheapest~ 300 mK
+
Previous State of the Art
hot
S N
A.M Clark, et al, Appl Phys Lett 86, 1734508 (2005)N.M. Miller, et al, Appl Phys Lett 92, 163501 (2008)
-NIS cooled X-Ray detector hasbest 6keV resolution with cryostat above 200mK:9.4 eV @ 6keV-Representative of a class sensors that operate near 100mK
230 mK
320 mK
160 mK
rest of chip = 260mK
cold
Tc=185mKDissipating 22 pW
How does it work?Vbias=.5Δ/e
eVbias
2
BCS DOS BCS DOSBCS DOS
Hot Electrons TunnelVbias=.9Δ/e
eVbias
2
BCS DOS BCS DOS
Normal Metal Cools - Superconductor HeatsVbias=.9Δ/e
eVbias
2
BCS DOS BCS DOS
Vbias=.9Δ/e
eVbias
2
BCS DOS BCS DOS
no bias on heatsinkjunction
Add a Heatsink (Quasiparticle Trap)
NIS Refrigerator Geometry
Si
Al-MnAl-Mn
SiO2
AlAl(Al-Mn)Ox
I
hot
hot
cold
Al-Mn
Old Thermal Model
normal metalelectrons
substrate/normal metalphonons (fixed at bath temperature)
superconductor(fixed at bathtemperature)
NIS Junction CoolingFunction of Tn
Electron-Phonon Coupling
IV Power
I2R
PayloadPower
Quasiparticle Return(Small Fraction of IV,Empirical)
New Thermal Model with Heatsink
normal metalelectrons
substrate/normal metalphonons (fixed at bath temperature)
superconductor(QP Density vsPosition)
NIS Junction CoolingFunction of Tn,Ts
Electron-Phonon Coupling
IV Power
I2R
normal metaltrap electrons(T vs Position)
Quasiparticle Trapping/(Heatsink)
Electron-Phonon Coupling
QuasiparticleRecombination
PayloadPower
Inside The Thermal Model
Si
Al-MnAl-MnSiO2
Al-Mn
x
Al
quasiparticle:
Si
Al-MnAl-MnSiO2
AlAl(Al-Mn)OxI
hot
hot
cold
Al-Mn
Predictions of Model
Previous 50nm
Target 25nm
Predictions of Model
Previous OverlayerOxide(no overlayer trap)
Target for overlayer10 m2
Si
Al-MnAl-MnSiO2
AlAl(Al-Mn)OxI
hot
hot
cold
Al-Mn
Measured Cooling to 112 mK
Record NIS Cooling(Large Junction)
T NIS=T ADR
Sat July 30 2010
2008
300 mK ↓
112 mK
Next Step:NIS Cooled Cryogenic Stage
•3mm chip -> 0.1uW @ 100 mK•10 uW dissipated at 300mK
NIS Junction Cooling Function of Tn