Single-electron tunneling through molecular quantum dots in a metal-insulator-semiconductor structure

A sigle-electron tunneling (SET) in a metal-insulator-semiconductor (MIS) structure is demonstrated, in which C₆₀ and copper phthalocyanine (CuPc) molecules are embedded as quantum dots in the insulator layer. The SET is found to originate from resonant tunneling via the energy levels of the embedded molecules, (e.g., the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO)). These findings show that the threshold voltages for SET are tunable according to the energy levels of the molecules. Furthermore, SET is observable even near room temperature. The results suggest, together with the fact that these properties are demonstrated in a practical device configuration, that the integration of molecular dots into the Si-MIS structure has considerable potential for achieving novel SET devices. Moreover, the attempt allows large-scale integration of individual molecular functionalities. Single-electron tunneling via molecular quantum dots is successfully demonstrated in a practical device configuration of a metal-insulator-semiconductor structure. The phenomenon is observable up to 280 K, which is almost room temperature. Based on these attractive features, our device can be regarded as a prototype device for "More than Moore", in which molecular functionalities can be integrated into Si-based devices.