Characteristics of Lateral Transport in In_(0.35)Ga_(0.65)As/GaAs Quantum Dot Heterostructures with Variation of Size, Shape and Density of Quantum Dots

摘要

Using the temperature dependent Hall (TDH) effect and low temperature magneto-resistance (MR) measurements, lateral transport studies in In_(0.35)Ga_(0.65)As/GaAs quantum dot (QD) heterostructures were performed as a function of the in plane direction. Correlations between the anisotropic behavior of the electron mobility and the elliptical shape of InGaAs QDs were revealed through temperature variations. In addition, the lateral anisotropy is demonstrated to depend on the QD density. Possible mechanisms of the transport through the QD layer are discussed. The high temperature conductivity in heterostructures with QDs behaves quite differently than bulk GaAs and quantum well (QW) heterostructure and is dependent on the areal density of the dots. At low temperatures and high magnetic fields, the integer quantum Hall effect (IQHE) was measured in the Hall resistance and varies with the size and density of QDs. In addition, a negative longitudinal MR at low temperatures and low magnetic fields is found, dependent on the structural properties of the nanostructures. This occurrence of negative MR is most likely due to the weak localization of charged carriers and needs further investigations.