Coulomb Blockade thermometer

Aivon offers Coulomb Blockade thermometers (CBT) for primary temperature measurements in temperature range 40 mK – 1 K. CBTs also tolerate high magnetic field (tens of Teslas magnetic field). Low-noise current preamplifier (PA1) can be used with SR830 lock-in amplifier and free CBT reader software for measuring the temperature and saving the data into file. Temperature can be measured easily with our graphical software, preamplifier, SR830 lock-in-amplifier and GPIB cable connecting the SR830 and computer.

The advantages of CBT are
- primary thermometer does not need calibration
- insensitivity to magnetic field
- simple conductance measurement using lock-in amplifier

The sensors are equipped with built-in ESD diodes and packaged in gold plated copper enclosures. Depending on the customer setup and requirements, different sensor packages are available.

From left: Uncovered CBT sensor (holder/lid type H3L3), H3L3 as normally delivered, strong permanent magnet is glued on top of the lid (H3L3m) to suppress superconductivity at temperature below 1 K, and bobbin for anchoring wire thermally into cryostat.

Products

H3L3 sensor package contains H3L3 sensor, bobbin B1 and 2 copper screws M4X12 and M4X20.
H3L3m sensor package contains H3L3 sensor with magnet, bobbin B1 and 2 copper screws M4X12 and M4X20.
B1 bobbin can also be purchased separately with minimum order of 5 pieces.
Copper screws CuM4X12 and CuM4X20 can also be purchased separately with minimum order of 10 pieces.
PA1 current preamplifier includes the preamplifier PA1, a power cable between lock-in amplifier and PA1 and a USB memory stick containing CBT reader software.

Do not hesitate to contact us if you are interested in quotation.

Downloads and updates

Please see the downloads page for manuals and freely available CBT reader software.

Brief theory

CBT is based on change of electric conductance of tunnel junction arrays. In CBT, the differential conductance of tunnel junction array is a bell-shaped curve.

Normalized conductance at three temperatures.

It has been shown [1], that the full-width at half maximum (V_1/2) of the curve depends only on the (electronic) temperature of the sensor and on some constants of nature.

V_1/2 = 5.439 N k_BT/e,                                                  (1)

where N is the number of tunnel junctions in the array, Boltzmann constant k_B = 1,38 exp(-23), T is the temperature and electron charge e=1,609 exp(-19).

Equation (1) forms the basis for primary thermometer since temperature can be calculated when the width of the conductance curve is measured. For faster measurements one can monitor only the depth of conductance dip at zero bias which depends on capacitance and temperature. The initially unknown capacitance can be calibrated once the temperature is measured using equation (1).

Current preamplifier PA1

CBT Reader software: Main panel and Controls panel shown

[1] J. Pekola et al, Physical Review Letters, 73, 2903 (1994)]