  We report electron transport measurements of a silicon double dot formed in
multi-gated metal-oxide-semiconductor structures with a 15-nm-thick
silicon-on-insulator layer. Tunable tunnel coupling enables us to observe an
excitation spectrum in weakly coupled dots and an energy level anticrossing in
strongly coupled ones. Such a quantum dot molecule with both charge and energy
quantization provides the essential prerequisite for future implementation of
silicon-based quantum computations.
