The development of primary thermometers, using disordered tunneling junction arrays

An important problem in the application of nanometersized-junction arrays to Coulomb blockade thermometry (CBT) is dispersion in the junction parameters. The performance of CBT is investigated by calculating two primary thermometric quantities, half-width V1/2and the third zero-crossing voltage V3,0of the I-V curve, for disordered junction arrays. The results show that the fluctuations of the two quantities among disordered parallel-connected array groups are considerably reduced in comparison to the case of individual one-dimesional (1D) disordered arrays. If the inhomogeneity of the junction is assumed to be ±20%, among the simulated samples of disordered array groups the relative fluctuation of V1/2and V3,0is only about 0.1%, and the mean values of V1/2and V3,0deviate positively from the ideal value in the uniform junction array by 3 and 4%, respectively. Therefore, the performance of CBT can be improved by connecting the arrays to form junction array groups, and high-quality CBT device can be made from the array group.