Temperature dependence of low-frequency noise in Al-Al2O3-Al single-electron transistors

We have measured the temperature dependence of the charge noise power spect ral density S-q in two-junction Al-Al2O3-Al single-electron transistors at temperatures from 85 mK to 4 K. Although individual Lorentzians are often v isible, the noise spectra are dominated by excess low-frequency noise with a power-law dependence on frequency f where S-q proportional to1/f(beta) an d beta similar or equal to1. Below about 0.5 K, S-q is weakly dependent on the temperature T. Above 1 K, the charge noise S-q increases with T, and at 4 K S-q approximate to 10(-4) e(2)/Hz at 1 Hz, about a factor of 100 great er than at 85 mK. (C) 2000 American Institute of Physics. [S0021-8979(00)04 521-7].