Pumping properties of the hybrid single-electron transistor in dissipative environment

Pumping characteristics were studied of a hybrid normal-metal/ superconductor single-electron transistor embedded in high-Ohmic environment. Two 3 μm long microstrip resistors of CrOx with a sum resistance R≈80 k were placed adjacent to the transistor. Substantial improvement of pumping and a reduction of the subgap leakage were observed in the low-megahertz range. At higher frequencies (0.1-1 GHz), pumping performance deteriorated compared to reference devices without resistors by the slowdown of tunneling and by electronic heating.