Growth and characterization of boron nitride thin films and nanostructures using atomic layer deposition = Bor nitrür ince filmlerin ve nanoyapıların atomik katman biriktirme yöntemi ile büyütülmesi ve karakterizasyonu
Author
Haider, Ali
Advisor
Bıyıklı, Necmi
Date
2014Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
159
views
views
287
downloads
downloads
Abstract
Being a member of III-nitride family, boron nitride (BN) and its nanostructures
have recently attracted a lot of attention, mainly due to their distinctive and
superior material properties, including wide band gap, high-temperature
stability, high oxidation and corrosion resistance, as well as high thermal
conductivity. This versatile material has found applications in UV emission,
lubrication, composite reinforcement, gas adsorption, cosmetics, and thermal
management. For modern electronic applications, it is imperative to obtain high
quality BN films on large area substrates with a controlled thickness in order to
fulfill the entire spectrum of hBN applications. Also, a facile method such as
atomic layer deposition (ALD) using non halide precursors is necessary to
obtain BN films at low temperatures compliant with the standards in terms of
having nontoxic byproducts. ALD is a special case of chemical vapor deposition
(CVD), in which two or more precursors are sequentially exposed to substrate
surface separated by purging periods. In comparison with other thin film growth
methods, hall mark of ALD is self limiting growth mechanism which enables
deposition of highly uniform and conformal thin films with sub-angstrom
thickness control. The precise and conformal layer by layer growth of ALD can
be exploited to achieve growth of BN hollow nanofibers (HNFs) on high aspect
ratio electrospun polymer nanofibrous templates. BN HNFs fabricated by
combination of ALD and electrospinning can be utilized to address and solve
important constraints associated with previous methods of fabrication such as severe preparation conditions, limited control over morphology, and low purity
of the resulting BN HNFs.
In this thesis, we report on the controlled deposition of BN films and its
nanostructures with the use of a hollow-cathode plasma source integrated
(HCPA-ALD) reactor and present detailed materials characterization results of
deposited thin films and fabricated nanostructures. Depositions are carried out at
low substrate temperatures (less than 450 °C) using sequential injection of nonhalide
triethylboron (TEB) and N2/H2 plasma as boron and nitrogen precursors,
respectively. The deposition process parameters such as pulse length of TEB and
substrate temperature, as well as the influence of post-deposition annealing are
studied. Moreover, another nonhalide alternative precursor named
tris(dimethyl)amidoboron (TDMAB) was studied for deposition of BN films.
Initial experiments were performed using TDMAB and N2/H2 plasma as boron
and nitrogen precursor. In addition to BN thin film growth studies, we report on
electrospun polymeric nanofibrous template-based fabrication and
characterization of AlN/BN bishell HNFs. Synthesized AlN/BN bishell HNFs
were found to be polycrystalline with a hexagonal structure along with lowimpurity
content.
Keywords
Plasma-Enhanced Atomic Layer DepositionChemical Vapor
Deposition
Boron Nitride
Thin Film
Nanofiber