Real Space Transfer Devices in Soi

Three-terminal real-space transfer (RST) devices employ charge injection of hot electrons over a potential barrier into an independently contacted second conducting layer. The first conducting layer is the usual transistor channel, where electrons are heated by the source to drain field. The high RST injection is accompanied by a strong negative differential resistance (NDR) in the source-drain circuit. Because of the NDR property, RST transistors can be used, e.g., as voltage-controlled oscillators for wireless applications. Efficiency of the RST has been amply demonstrated in III-V heterostructures, where bandwidths in excess of 100 GHz have been demonstrated. Silicon implementations of RST have been so far limited to the Si/GeSi heterosystem. In this paper I discuss possible implementation of RST transistors in Si, using low-barrier dielectrics, such as zirconium silicates, which are currently under intensive investigation in the context of the high-κ dielectrics program. SOI technology offers special advantages both for the implementation of RST devices and their likely application.