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Title: Surface-acoustic-wave (SAW) driven light sources
Author: Gell, Jennifer Rachel
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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This thesis concentrates on the interaction between SAWs (surface acoustic wave) and low-dimensional systems studied using optical techniques. In particular SAW-driven luminescence from a lateral p-n junction is demonstrated. The lateral p-n junction is formed by molecular beam epitaxy regrowth on a patterned GaAs substrate. Silicon is used as an amphoteric dopant to create a high mobility two-dimensional electron gas on flat (100) planes and a two-dimensional hole gas on angled (311)A facets. A lateral p-n junction is formed at the interface between these planes. SAWs with a frequency of ~1 GHz are generated using an interdigitated transducer. When a continuous radio frequency (RF) signal is used to excite the transducer, SAW-driven light emission from the p-n junction is demonstrated by peaks in the current/light emission at the resonant frequency of the transducer. To investigate the nature of the luminescence further, short RF pulses are used to drive the transducer. The short pulses temporally isolate the SAW-driven light emission from any emission due unwanted pick-up of the free space electromagnetic wave. In the final section the modulation of the emission energies of a single self-assembled quantum dot by a SAW is investigated. The compression and expansion of the crystal due to the strain wave causes the energy of the dot lines to oscillate around their equilibrium values. The shape of the SAW broadened emission lines was seen to depend on the nature of the transition in the dot offering an alternative way of identifying charged and neutral species in this sample. The modulation of the dot energy levels by the SAW is used to control the time of photon emission from the system.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available