Thursday, January 21, 2010

Wow. Impressive room-temperature single-electron device

Looking at the arxiv this evening, I came across this paper, in which the authors demonstrate a silicon-based single-electron transistor that operates at room temperature.  The device is fabricated from a "finFET", a transistor design put forward for ultrascaled CMOS electronics.  In a finFET, the silicon channel is surrounded on three sides by a wrap-around gate, to achieve comparatively efficient gate coupling.  A single-electron transistor is very different from an ordinary field-effect transistor.  The channel in a SET is an "island" connected via tunnel barriers to source and drain electrodes.  The island has some capacitance, C, and therefore there is an energy cost associated with putting an additional electron on the island given by e2/2C.  If that energy cost is large compared to kBT, and the tunnel barriers are sufficiently opaque (so that lifetime broadening doesn't smear out the island spectrum), then one can see single-electron charging effects in the conduction.  When the island is very small, one has to worry not just about the Coulomb charging energy, but also about the particle-in-a-box level spacing on the island.  (Note that all of this discussion is assuming that electron-electron interactions can be lumped together simply, via the capacitance.)

The impressive part of this work is just how clean the SET characteristics look at 300 K.  Getting clean SET signatures in conduction requires the thermal energy scale to be at least 20 times smaller than the charging energy scale, and at 300 K that's a tall order!  The data in Fig. 2c are spectacular for a room temperature SET device.  Very very pretty.  If they can figure out how to do this reliably, there are many exciting possibilities.... 

1 comment:

CarlBrannen said...

This is an impressive achievement, one that I'm sure we can expect to see a lot of work develop from. I'm only commenting here because no one else has, but I'm sure everyone appreciates the post.