Observation of Coulomb-blockade in a field-effect transistor with silicon nanocrystal floating gate at room temperature

In a field-effect transistor (FET), six single electron-tunneling events and the corresponding electron storage in silicon nanocrystals were observed at room temperature. The device is a metal-oxide-semiconductor field-effect transistor (MOSFET) with an electron channel 5 μm in length, 10 μm in width, and an array of silicon-oxide passivated silicon nanocrystals as the multiple-nanocrystal floating gate. The layer of silicon nanocrystals with an average size of 5 nm is prepared by plasma enhanced chemical vapor deposition (PECVD) method using high-hydrogen diluted silane and followed by thermal treatment. Because of the ultra-small electric capacitance (about 4.6×10-2 aF) between the control gate and a single nanocrystal, the tunneling of electrons from the channel to the nanocrystals is regulated by the Coulomb-blockade effect. The addition of one more electron per nanocrystal leads to the oscillation of the drain-source current with a period of 3.8 V and causes a shift of 1.3 V in the threshold voltage. The duration of the electron storage in the nanocrystal is longer than 20 min.