  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.
