A high-mobility (9000 cm 2 /V‚s) semiconducting single-walled nanotube transistor is used to construct a nonvolatile charge-storage memory element operating at room temperature. Charges are stored by application of a few volts across the silicon dioxide dielectric between nanotube and silicon substrate, and detected by threshold shift of the nanotube field-effect transistor. The high mobility of the nanotube transistor allows the observation of discrete configurations of charge corresponding to rearrangement of a single or few electrons. These states may be reversibly written, read, and erased at temperatures up to 100 K.Decreasing the power required to write and erase memory devices requires either a reduction of the write voltage or a reduction in the number of electrons representing one bit. The former is fundamentally limited by the thermal energy at room temperature, and efforts have focused on the latter. The ultimate reduction, i.e., the storage of a single electronic charge, offers advantages over storing quasi-continuous quantities of charge: 1 the Coulomb energy associated with adding additional charges to the storage node can be used to guarantee a discrete charge state, 2 and the quantized nature of the charge stored makes the device characteristics less sensitive to the details of the device structure. However, the operation of a single-electron memory at useful temperatures presents two major challenges: the capacitance of the storage node must be small enough that its Coulomb charging energy is significantly larger than the thermal energy at the operating temperature, and the readout device must be sufficiently sensitive to detect a single nearby electronic charge. Efforts to date have focused on floating-gate charge storage nodes either patterned lithographically 3-5 or formed serendipitously in a polycrystalline channel. 1 Detection of single charges at elevated temperatures has been demonstrated with singleelectron transistors 5 or very narrow silicon-or polysiliconon-insulator field-effect transistors (FETs). 1,3,4 However, single-electron transistors that can operate at room temperature remain extremely difficult to fabricate, and the fieldeffect transistors demonstrated so far have modest mobilities.Here we report on a charge-storage memory using a single semiconducting nanotube FET as the readout. Charge is reversibly injected and removed from the dielectric by applying a moderate voltage (<10 V) across the dielectric between nanotube and substrate. The nanotube FET is ideal as a charge detecting device; it has extremely high mobility (e.g. 9000 cm 2 /V‚s for the device described here), large geometrical capacitance, and its one-dimensional nature guarantees that local changes in charge density affect the global conductance. In the device reported here, discrete charge states corresponding to differences of a single or at most a few stored electrons are observed and can be written, read, and erased at temperatures up to 100 K, with changes in current of more than 50 nA. This rather ...

Single-walled carbon nanotubes (SWNTs) have been grown via chemical vapor deposition on high-κ dielectric SrTiO 3 /Si substrates, and high-performance semiconducting SWNT field-effect transistors have been fabricated using the thin SrTiO 3 as gate dielectric and Si as gate electrode.The transconductance per channel width is 8900 µS/µm. The high transconductance cannot be explained by the increased gate capacitance; it is proposed that the increased electric field at the nanotube-electrode interface due to the high-κ SrTiO 3 decreases or eliminates the nanotubeelectrode Schottky barrier.