Lateral Surface Superlattices in Strained InGaAs Layers

Milton, Brian (2000) Lateral Surface Superlattices in Strained InGaAs Layers. PhD thesis, University of Glasgow.

Abstract

Lateral Surface Superlattices were fabricated by etching in strained InGaAs layers above a GaAs/AlGaAs 2DEG channel. These were etched both by dry plasma wet chemical etching to produce periods of l00nm, 200nm and 300nm. These superlattices were fabricated on Hall bars to allow four terminal measurement and a blanket gate was placed on top, to allow variations in the carrier concentration. The magnetoresistance effects of these superlattices were studied at varying values of gate voltage, which varies the carrier concentration and the electrostatic periodic potential and at temperatures down to 45mK in a dilution refrigerator. From the oscillations observed in the magnetoresistance traces it is possible to calculate the magnitude of the periodic potential. This showed that the etched, strained InGaAs was producing an anisotropic piezoelectric potential, along with an isotropic electrostatic potential. The variation in period allowed a study of the change of this piezoelectric potential with the period as well as a study of the interactions between the electrostatic and piezoelectric potentials. Further, at the lowest temperatures a strong interaction was observed between the Commensurability Oscillations, caused by the periodic potential, and the Shubnikov-de Haas Oscillations due to the Landau Levels. This interaction was studied as it varied with temperature and carrier concentration.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: Andrew Long
• Keywords: Condensed matter physics
• Date of Award: 2000
• Depositing User: Enlighten Team
• Unique ID: glathesis:2000-76016
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Nov 2019 17:07
• Last Modified: 19 Nov 2019 17:07
• URI: https://theses.gla.ac.uk/id/eprint/76016