Study on Cold-Finger ³He Cryostat for Precision Measurements of Quantum Hall Resistance and Single-Electron Pump Current

The performance of our newly constructed cold-finger cryostat is investigated for the precision measurement of quantum Hall resistance (QHR) and single-electron pump (SEP) current. The cryostat is featured by a vacuum sealed sample chamber that is attached to the 0.3 K-plate inside the inner vacuum can. The nominal base temperature of the sample chamber was 0.4 K. However, the electron temperature estimated with a single-electron transistor was approximately 0.6 K. Precision evaluation of a GaAs QHR device shows that the quantized Hall resistance is equivalent to the nominal value of h/2e ² within one part in 10 ⁸ . The Allan deviation data for the SEP current is analyzed to be greater than those obtained from SEP in a wet ³ He cryostat at Korean Research Institute of Standards and Science.