The Transport Properties of Electrons and Holes in a Silicon Quantum Well

Abstract

Semiconductors have revolutionised the field of electronics due to the nature of their readily engineerable bandstructure. Additionally, the study of the 2D charge systems hosted by devices made from these materials has led to the discovery of fundamental physics of these systems. Silicon has been at the forefront of developments in this field owing to its natural abundance, ease of processing and naturally occurring oxide. In this thesis a double gated, metal oxide semiconductor field effect transistor (MOSFET) is used to investigate a number of transport properties of electrons and holes. These include the transport properties of a single layer within a bilayer system, the control of the hole g∗m∗ with the MOSFET gates and probing of the effects of giant valley splitting on the electrons.

Bilayer systems are composed of two single, physically separate, layers of charge carriers contained within the same quantum well. Their study has provided insight into carrier inter actions between the layers with the potential for use in vertically coupled systems of charges in novel electronic devices. Here the effects of one layer on the I-V characteristics of the other are described.

Direct control of the electron or hole spin via the gates of a transistor was first proposed by Datta and Das. Although such a device has yet to be fully realised, control of the g∗m∗ has been demonstrated in a number of materials. Here the control of the hole g∗m∗ is demonstrated on the (001) silicon plane for the first time.

Giant valley splitting is an effect whereby the valley degeneracy of the electrons in silicon is lifted. In this thesis, the effects of giant valley splitting is shown to have a similar phenomenological effect on the resistivity of a 2D electron gas as spin splitting does on the same, valley degenerate system.

Date of Award	3 Jul 2014
Original language	English
Awarding Institution	University of Bath
Sponsors	Nippon Telegraph and Telephone Corporation
Supervisor	Kei Takashina (Supervisor) & Alain Nogaret (Supervisor)