eprintid: 10100241
rev_number: 8
eprint_status: archive
userid: 695
dir: disk0/10/10/02/41
datestamp: 2020-06-10 08:39:29
lastmod: 2020-06-10 08:39:29
status_changed: 2020-06-10 08:39:29
type: thesis
metadata_visibility: show
creators_name: Roberts, Jason Mark
title: Electronic properties of quantum wells for field effect transistor applications
ispublished: unpub
keywords: (UMI)AAI10045788; Applied sciences; Field effect transistor applications; Quantum wells
note: Thesis digitised by ProQuest.
abstract: Several alternative techniques for improving the transport properties of delta-doped quantum well structures have been investigated. The most successful have used edge delta-doping and compositional grading to produce significantly enhanced electron transport characteristics in AlxGa1-xAs/GaAs, AlxGa1-xAs/InyGa1-yAs, and Al xIn1-xAs/InyGa1-yAs quantum well structures. This compositional grading has been achieved using the digital alloying growth technique—which has been confirmed as a viable method of producing good quality, delta-doped material. Improvements of up to 100% in mobility (to 2630cm2/Vs) and 67% in electron saturation drift velocity (to 1.7 × 107 cm/s) have been achieved using these techniques. The dependence of electron saturation drift velocity (vsat) on mobility (μ) has been determined as vsat α μ0.8±0.3. In addition, we present our investigations of the free-carrier loss observed in a series of highly Si delta-doped AlxGa1-xAs/GaAs quantum well structures. We interpret the results of Hall measurements and self-consistent Poisson Schrodinger modelling in terms of a model of DX centre formation which includes Coulomb interactions, a result of the charged nature of the DX state. Our interpretation implies a strongly growth dependent DX centre energy—which explains the range in published values for the GaAs DX centre energy. The data allows investigation of the DX centre distribution between 214 and 249 meV above the F minima, and confirms a considerably broadened DX centre density of states ≥35 meV).
date: 1997
oa_status: green
full_text_type: other
thesis_class: doctoral_open
thesis_award: Ph.D.
language: eng
primo: open
primo_central: open_green
verified: verified_manual
full_text_status: public
pages: 199
institution: University College London (United Kingdom)
thesis_type: Doctoral
citation:        Roberts, Jason Mark;      (1997)    Electronic properties of quantum wells for field effect transistor applications.                   Doctoral thesis  (Ph.D.), University College London (United Kingdom).     Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/10100241/1/Electronic_properties_of_quant.pdf