Towards a silicon quantum computer

• Main Author: George, R. E.
• Published: University of Cambridge 2009
• Subjects: 004.01
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599362

This thesis investigates the properties of electrons in silicon with a view to their use as quibits in a prospective quantum computer. The thesis first investigates the properties of Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) devices doped with sodium, characterising bound-states formed by the presence of sodium ions though studying the temperature dependence of the device conductivity as s function of carrier density. The thesis then studies Electron Paramagnetic Resonance (EPR) of sodium doped silicon devices, searching for a resonance from the sodium bound-states, and determining the effect of moving the sodium atoms on the spectrogram, finding no sharp resonance due to the presence of sodium, but detecting the effects of the sodium drifting procedure on related E’ interface states. The EPR technique is then used to characterise the resonance from a related silicon-germanium sample containing an electron gas and point defects that has application as a standard reference sample containing an accurately determined number of spins. The work turns to fabricating and characterising Single Electron Transistor (SET) devise in silicon, with a view to application as a sensitive electrometer for use in a spin to charge conversion measurements. The device shows a magnetic field dependent oscillation in conductivity, consistent with the electron phase coherence length being larger than the dimensions of the SET at the lowest temperatures used. The document concludes with a review and suggestions for further work.