Ambipolar quantum dots in intrinsic silicon
  We electrically measure intrinsic silicon quantum dots with electrostatically defined tunnel barriers. The presence of both p-type and n-type ohmic contacts enables the accumulation of either electrons or holes. Thus we are able to study both transport regimes within the same device. We investigate the effect of the tunnel barriers and the electrostatically defined quantum dots. There is greater localisation of charge states under the tunnel barriers in the case of hole conduction leading to higher charge noise in the p-regime. 
A. C. Betz, M. F. Gonzalez-Zalba, G. Podd, A. J. Ferguson
cond-mat.mes-hall