Thermal and Electrical Performance Study of Cold-Finger ³He Cryostat in Precision Measurement of Quantum Hall Resistance and Single-Electron Current

The performance of our newly constructed cold-finger cryostat is investigated for quantum Hall resistance (QHR) and single-electron pump (SEP) devices. The cryostat features a vacuum-sealed sample chamber (SC) attached to a 0.3 K plate inside the inner vacuum can. The SC is designed to accommodate both the SEP and the QHR devices with a shielding partition between them. The measured QHR in the chamber approaches the nominal value for filling factor 2 within 20 parts in 10
⁹
. The white-noise level of the SEP module, as obtained from the Allan deviation data, is 4.5 fA/
$\sqrt {\mathrm{ Hz}}$
. We also investigated the thermometry of the SC either under vacuum or filled with
³
He gas. We calculated the thermal conductivity of the different heat conduction channels in the sample holder and found the dominant channel to be through the chip carriers not signal lines.