Development of single electron devices and their application as low noise electrometers

As electronic devices become extremely small, the charging energy associated by putting a single electron on the device can change its transport properties. In the extreme limit, when the energy is much larger than the energies associated with thermal and quantum fluctuations, the motion of charges is restricted. A new kind of electronics has emerged in this regime where the operation of devices is based on single electron effects. The most important example is a single electron transistor (SET) which is a highly sensitive electrometer.; My thesis focused on electrometer applications of SETs and related devices. In addition to investigating SETs, I introduced a new electrometer, called a quantum point contact (QPC) transistor. This device can have a voltage gain greater than one and charge sensitivity close to the quantum limit, which is comparable to the SET. However, multiple QPC transistors can be easily operated in parallel since they do not suffer from offset charges.; As required by its operation principle, the input capacitance of SETs is extremely small making them impractical for a majority of electrometer applications where the devices are macroscopic. To address this capacitance matching problem, we invented a charge transformer (CT) to be placed between the macroscopic device and the SET. A prototype is fabricated with 4 capacitors and 13 switches, which achieved perfect noise matching with a voltage step up ratio that approached 4. In addition, I fabricated a coupled quantum dot device to investigate a new type of noise introduced by the CT.; I investigated various fabrication issues related to SETs. To achieve room temperature operation of SETs, the devices need to be scaled down to the sub nanometer range. To address this issue, we fabricated nanogap electrodes by selective etching of a GaAs/AlGaAs heterostructure and link the device by trapping gold nanoparticles between the electrodes. We successfully trapped a nanoparticle which was signaled by a resistance change of a few orders of magnitude. Finally, to investigate noise properties of electron systems in the fractional quantum Hall regime we needed low noise electrometers. To this end, I have integrated Al/AlOx/Al SETs with GaAs/AlGaAs devices.