From wave-functions to current-voltage characteristics in silicon single-nanocrystal Coulomb blockade devices

In the search for innovating solutions likely to ensure the perenniality of silicon microelectronics which will have to face up to technological as well as theoretical limits within a few years, the concept of semiconductor single-electron devices has revealed promising assets (Choi et al., 1998 and Ohba et al., 2002). By exploiting the electric charge granularity through Coulomb blockade phenomenon, these type of devices may offer new functionalities or even an alternative to CMOS circuits while remaining compatible with current technologies. From this point of view, a theoretical examination by various approaches of physical simulation appears to be of first interest in order to predict the behavior of these future generation devices and to give information on the appropriate design (Deleruyelle et al., 2004). This work aims at studying elementary metal-insulator-silicon quantum dot-insulator-metal (MIS/IM) structures thanks to a physical description using only fundamental parameters of the system (oxide thicknesses, metal work function, quantum dot size and shape, temperature, ...). The model consists in calculating: (i) the electronic structure of Si nanocrystal using the Hartree method (See et al., 2002); (ii) the tunneling transfer rates in Bardeen's approach (Bardeen, 1961); and (iii) the current using a Monte-Carlo technique. The main advantage of this approach lies in the accurate calculation of tunneling rates including the effect of bias voltage on the wave-functions in the quantum dot and tunnel barriers (See et al., 2004).