Atomic layer deposition of metal oxides for optoelectronic device applications
File(s)
Author(s)
Kainth, Jaspreet
Type
Thesis
Abstract
Atomic layer deposition is a vapour phase thin film deposition technique that has continued
to gain popularity over the past few decades due to its unique combination of properties. It
is based on self-saturating surface reactions that enable layer-by-layer growth of a material.
Resultingly, ALD has excellent control over film thickness, and is able to grow uniform and
conformal films over complex and high aspect ratio structures. ALD has emerged as a prime
candidate for the deposition of metal oxide thin films with a number of precursor materials now
commercially available for use in thermal ALD systems. This study focuses on the growth of
zinc oxide (ZnO) and aluminium-doped zinc oxide (AZO) for optoelectronic applications.
Initial work was based on the investigation of the process-property relationship in the growth
of ZnO and AZO films with particular focus on the morphological, structural and electrical
properties obtained from these materials. It was observed that by varying the film thickness and
deposition temperature of ZnO films, the film structure and semiconducting properties could be
tuned. Interestingly, it was found that under certain deposition conditions that the electrical
behaviour of ZnO transitioned from semiconducting to conducting. The growth of AZO was
also explored utilising the delta doping method in which the ratio of the ALD precursors was
varied in order to incorporate varying amounts of aluminium into the films. The deposition
temperature of these AZO films was also studied. It was found that by carefully selecting the
right combination of deposition conditions the optical and electrical properties of AZO films
could be tuned for successful application as a transparent, conducting oxide electrode...
to gain popularity over the past few decades due to its unique combination of properties. It
is based on self-saturating surface reactions that enable layer-by-layer growth of a material.
Resultingly, ALD has excellent control over film thickness, and is able to grow uniform and
conformal films over complex and high aspect ratio structures. ALD has emerged as a prime
candidate for the deposition of metal oxide thin films with a number of precursor materials now
commercially available for use in thermal ALD systems. This study focuses on the growth of
zinc oxide (ZnO) and aluminium-doped zinc oxide (AZO) for optoelectronic applications.
Initial work was based on the investigation of the process-property relationship in the growth
of ZnO and AZO films with particular focus on the morphological, structural and electrical
properties obtained from these materials. It was observed that by varying the film thickness and
deposition temperature of ZnO films, the film structure and semiconducting properties could be
tuned. Interestingly, it was found that under certain deposition conditions that the electrical
behaviour of ZnO transitioned from semiconducting to conducting. The growth of AZO was
also explored utilising the delta doping method in which the ratio of the ALD precursors was
varied in order to incorporate varying amounts of aluminium into the films. The deposition
temperature of these AZO films was also studied. It was found that by carefully selecting the
right combination of deposition conditions the optical and electrical properties of AZO films
could be tuned for successful application as a transparent, conducting oxide electrode...
Version
Open Access
Date Issued
2021-11-10
Date Awarded
01/02/2023
License URL
Advisor
McLachlan, Martyn
Heeney, Martin
Publisher Department
Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)