  We report on ambipolar gate-defined quantum dots in silicon on insulator
(SOI) nanowires fabricated using a customised complementary
metal-oxide-semiconductor (CMOS) process. The ambipolarity was achieved by
extending a gate over an intrinsic silicon channel to both highly doped n-type
and p-type terminals. We utilise the ability to supply ambipolar carrier
reservoirs to the silicon channel to demonstrate an ability to reconfigurably
define, with the same electrodes, double quantum dots with either holes or
electrons. We use gate-based reflectometry to sense the inter-dot charge
transition(IDT) of both electron and hole double quantum dots, achieving a
minimum integration time of 160(100) $\mu$s for electrons (holes). Our results
present the opportunity to combine, in a single device, the long coherence
times of electron spins with the electrically controllable holes spins in
silicon.
