Electronic transport in self-assembled quantum dots

This dissertation discusses electron transport measurements in InAs self-assembled quantum dots. Strain induced clustering of InAs grown on GaAs results in coherent, defect free islands approximately 300Å diameter. The dots are grown in close proximity (100Å) to a two dimensional electron gas (2DEG) at a GaAs/AlGaAs heterojunction. The 2DEG is laterally patterned with fine metal gates and shallow trenches fabricated using electron beam lithography.; Two types of measurements are made: conductance and electron phase. For the conductance experiments quantum dots are isolated both in narrow constrictions in the 2DEG and in long, narrow 2DEG channels. Conductance peaks corresponding to single electron tunneling are measured in both systems. In each case tunneling transport occurs through a strain-induced GaAs quantum dot formed in the 2DEG. In the narrow channels transport through the InAs quantum dot is also measured. Results are in good agreement with theoretical descriptions of quantum dot transport.; Phase measurements are made using rings lithographically defined in the 2DEG with quantum dots underneath. Aharonov-Bohm oscillations are measured. The phase coherence length is derived from both weak localization and universal conductance fluctuations in the channels. In both cases the phase coherence length at 100mK is approximately 2000Å. The temperature dependence fits well to standard theory of electron-electron scattering in 1D channels.