Electronics is based on switches, which can turn on and off signals. The smaller the switches are, the more complex circuits can be realized. However, with increasing miniaturization of electronic circuits an increasing fraction of the applied power is converted into nondeterministic signals and heat that add to the ambient noise. In commonly used device concepts noise degrades the performance. Interestingly, there are cases where noise can lead to enhanced signal to noise ratios, if principles of Stochastic Resonance (SR) are used: External signals synchronize noise. Based on this concept, the EU funded STREP project SUBTLE is associated with nanoelectronic devices in which quantum-confined electron channels are so closely spaced to each other that tailored feedback action exists. The approach of SUBTLE is based on the application of two effects in miniaturized electronics, which one usually tries to avoid in device design:
back-action of the channel on the gate
noise induced switching
Scheme of a quantum-gate transistor realized within the SUBTLE project. Two quantum wells with the upper serving as transistor channel and the lower as gate were grown with atomic precision. Contacts were defined by new undercut technique, which allow to independently control the gate and the channel.
In order to make use of them and even to obtain signal gain, new types of switches are realized. By utilizing nonlinear transport in nanosystems the SUBTLE project has the potential to open a new window for electronic applications covering stochastic resonance phenomena, sub thermal switching and on chip noise control applications.