The Radio Frequency Single-Electron Transistor: Noise Properties and its Potential for Detecting Electrons on Helium
Abstract: In this thesis the noise in the single electron transistor (SET) has been investigated.The charge sensitivity for the radio frequency single electron transistor(RF-SET) was measured. The demonstrated result is better than the previouslybest reported value both at 40 mK, and at 4.2 K. The demonstratedcharge sensitivity at 40 mK is 0.9μe/√Hz a 5 times worse than theoreticallimit. The charge sensitivity at 4.2K is 1.8μe/√Hz only 1.6 times worse thenthe theoretical limit for this temperature.The SET was operated in the radio frequency mode which allowed tomeasure the low frequency noise of the SET in a wide frequency range fromfew Hz up to tenths MHz. Noise spectra were measured over a wide rangeof the gate voltage and bias voltage. In the data analysis we are able toseparate noise contributions from different noise sources in the SET.From the low frequency noise measurements, we conclude that the noisespectra at low frequencies (f ∼ 1 kHz) is determined by a single chargefluctuator close to our SET. The noise spectra at the frequency range (f >10 kHz) is dominated by resistance noise in the different junctions and wecan conclude that the excess noise comes from the resistance noise of one ofthe tunnel barriers.We have introduced a method of direct measurement of the shot noisein the SET at f = 350 MHz. We have measured the shot noise propertiesof the single electron transistor with high tunnel barrier transparencies; andcompared results with the orthodox theory for single electron tunneling.In the final part of this thesis preliminary results on experiments withelectrons above a superfluid helium surface is reported.
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