Statistics of Coulomb Blockade Peak Spacings

Distributions of Coulomb blockade peak spacings are reported for large ensembles of both unbroken (magnetic field B ­ 0) and broken (B fi 0) time-reversal symmetry in GaAs quantum dots. Both distributions are symmetric and roughly Gaussian with a width of ,2% 6% of the average spacing, with broad, non-Gaussian tails. The distribution is systematically wider at B ­ 0 by a factor of ,1.2 6 0.1. No even-odd spacing correlations or bimodal structure in the spacing distribution is found, suggesting an absence of spin degeneracy. There is no observed correlation between peak spacing and peak height. [S0031-9007(98)06083-9]