UK researchers are close to demonstrating controlled manipulation of electron spins in gated devices using the InAs and InSb family of narrow bandgap materials.

The lifetime of electrons with defined spins injected into these materials is significantly shorter than in wide gap semiconductors such as GaAs, but they offer other advantages.

"InAs is unique in that when a metal is put down on top of it, the contact is Ohmic and not a Schottky barrier," explained Dr Lesley Cohen, reader in solid state physics at Imperial College. "So it's a perfect template for creating designer barriers. You don't have to live with the natural barrier that all other semiconductors present."

The materials also have higher room temperature mobility, and the potential to control a spin with a gate once it is injected is much greater. Cohen said the reduced lifetime is far from a showstopper.

"It's in gating these structures where the real spin transistor applications are. A gate can go down comfortably to within a micron, so as long as you can drift it [a spin] in a micron in 10-100ps you should be all right."

Imperial is one of a handful of university groups pursuing InAs/InSb devices. "We are very close to demonstration," said Cohen.