Si-based single-electron devices with tunable barriers

Although single-electron devices have been pursued for metrology, nano-electronics and other applications, it has been difficult to find a way to make reproducible, reliable devices. We have recently made and demonstrated Si-based SET transistors with high yield, good reliability, and good uniformity as well. These devices are similar to Si MOSFETs, with the addition of tunable barriers formed by two layers of gates; the lower gates form the tunnel barriers, and the upper gate provides the inversion necessary for conduction. Having measured four devices to date, we have discovered that the nonuniformity of various device capacitances is less than 10 % (previous best was about 50 %) and that these devices have Ec ~ 20 K. The tunability of the barriers also provides an interesting playground for a wide variety of studies; we will report on some of these, possibly including the systematic evolution from single to double islands, the new concept of a "barrier capacitance", etc.