Detection of a large valley-orbit splitting in silicon with two-donor   spectroscopy
  We measure a large valley-orbit splitting for shallow isolated phosphorus donors in a silicon gated nanowire. This splitting is close to the bulk value and well above previous reports in silicon nanostructures. It was determined using a double dopant transport spectroscopy which eliminates artifacts induced by the environment. Quantitative simulations taking into account the position of the donors with respect to the Si/SiO$_2$ interface and electric field in the wire show that the values found are consistent with the device geometry. 
Benoit Roche, Eva Dupont-Ferrier, Benoit Voisin, Manuel Cobian, Xavier   Jehl, Romain Wacquez, Maud Vinet, Yann-Michel Nique...
cond-mat.mes-hall