A metal/oxide tunnelling transistor

We have fabricated a new type of nanometre-scale transistor that operates by using a gate field to modulate the tunnelling probability of electrons through a lateral metal/oxide tunnel junction. Computer simulations predict that such a tunnelling transistor should have operating characteristics similar to those of a Si MOSFET but should be scalable to similar to 10 nm gate lengths. The device is composed entirely of noncrystalline materials, thus facilitating fabrication on a variety of substrates and multilayer stacking of devices for three-dimensional circuit architectures. Our initial devices have a 40 nm wide Ti/TiOx tunnel junction on top of a planar Al2O3/Al buried gate. Application of gate bias results in an order of magnitude modulation of the source-drain tunnelling current at 77 K. However, the device transconductance is smaller than predicted by modelling, which we attribute to the gate field not fully penetrating to the active region of the tunnel junction.