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Full text release has been delayed at the author's request until August 06, 2025
ETD Abstract Container
Abstract Header
Metalorganic chemical vapor deposition of ultrawide bandgap (Al
x
Ga
1-x
)
2
O
3
for next generation power electronics
Author Info
Bhuiyan, A F M Anhar Uddin
ORCID® Identifier
http://orcid.org/0000-0003-3421-2813
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=osu1689886516141118
Abstract Details
Year and Degree
2023, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
Abstract
Beta-phase gallium oxide (β-Ga
2
O
3
), with its ultrawide band gap energy (~4.8 eV), high predicted breakdown field strength (6-8 MV/cm), controllable n-type doping and availability of large area, melt-grown, differently oriented native substrates, has spurred substantial interest for future applications in power electronics and ultraviolet optoelectronics. The ability to support bandgap engineering by alloying with Al
2
O
3
also extends β-(Al
x
Ga
1-x
)
2
O
3
based electronic and optoelectronic applications into new regime with even higher critical field strength that is currently unachievable from SiC-, GaN- or Al
x
Ga
1-x
N- (for a large range of alloy compositions) based devices. However, the integration of β-(Al
x
Ga
1-x
)
2
O
3
alloys into prospective applications will largely depend on the epitaxial growth of high quality materials with high Al composition. This is considerably important as higher Al composition in β-(Al
x
Ga
1-x
)
2
O
3
/Ga
2
O
3
heterojunctions can gain advantages of its large conduction band offsets in order to simultaneously achieve maximized mobility and high carrier density in lateral devices through modulation doping. However, due to the relative immaturity of β-(Al
x
Ga
1-x
)
2
O
3
alloy system, knowledge of the synthesis and fundamental material properties such as the solubility limits, band gaps, band offsets as well as the structural defects and their influence on electrical characteristics is still very limited. Hence, this research aims to pursue a comprehensive investigation of synthesis of β-(Al
x
Ga
1-x
)
2
O
3
thin films via metal organic chemical vapor deposition (MOCVD) growth methods, building from the growth on mostly investigated (010) β-Ga
2
O
3
substrate to other orientations such as (100), (001) and (-201), as well as exploring other polymorphs, such as alpha (α) and kappa (κ) phases of Ga
2
O
3
and (Al
x
Ga
1-x
)
2
O
3
to provide a pathway for bandgap engineering of Ga
2
O
3
using Al for high performance device applications. Using a wide range of material characterization techniques, experiments have been undertaken to investigate the physical structure, electronic and optical properties of Ga
2
O
3
and (Al
x
Ga
1-x
)
2
O
3
films, with the correlation to theoretical studies. Al compositions in (Al
x
Ga
1-x
)
2
O
3
films are varied for the whole range in order to understand the phase segregation at higher Al compositions as predicted by equilibrium phase diagram as well as theoretical studies. The Si doping in β-(Al
x
Ga
1-x
)
2
O
3
thin films is investigated as a function of Al compositions, with a goal to identify the major challenges associated with MOCVD epitaxy β-(Al
x
Ga
1-x
)
2
O
3
films, such as the formation of cracks, increase of the concentrations of planer defects, carbon and hydrogen densities, which are predicted to act as compensating acceptors in β-(Al
x
Ga
1-x
)
2
O
3
. In addition, the band discontinuities at β-(Al
x
Ga
1-x
)
2
O
3
/Ga
2
O
3
heterojunctions with various Al compositions are also determined along different orientations to understand the influence of substrate orientations on the band offsets. The growth of in-situ MOCVD Al
2
O
3
dielectric on differently oriented β-(Al
x
Ga
1-x
)
2
O
3
films have been investigated to gain insights into how varying orientations and Al compositions influence the interfacial quality and the band offsets at Al
2
O
3
dielectric/β-(Al
x
Ga
1-x
)
2
O
3
heterojunctions. Apart from β-(Al
x
Ga
1-x
)
2
O
3
epitaxy, the crystalline structure and quality of MOCVD grown single phase α-(Al
x
Ga
1-x
)
2
O
3
and κ-Ga
2
O
3
films are also investigated for potential applications in high-power and high-frequency electronics. Such findings will greatly assist in designing and fabricating future high power heterostructure based electronic and optoelectronic devices.
Committee
Hongping Zhao (Advisor)
Siddharth Rajan (Committee Member)
Steven A. Ringel (Committee Member)
Sanjay Krishna (Committee Member)
Pages
512 p.
Subject Headings
Condensed Matter Physics
;
Electrical Engineering
;
Engineering
;
Materials Science
;
Nanoscience
;
Nanotechnology
;
Physics
Keywords
Ultrawide bandgap
;
(AlxGa1-x)2O3
;
Ga2O3
;
metalorganic chemical vapor deposition
;
MOCVD
;
bandgap engineering
;
phase transformation
;
beta phase
;
Kappa phase
;
alpha phase
;
gamma phase
;
band offsets
;
Al2O3 dielectric
;
Si doping
;
STEM imaging
;
XPS
;
XRD
;
semiconductors
;
β-(AlxGa1-x)2O3
;
thin films
;
β-Ga2O3
;
epitaxy
;
MOVPE
;
κ-phase Ga2O3
;
α-phase Ga2O3
;
Recommended Citations
Refworks
EndNote
RIS
Mendeley
Citations
Bhuiyan, A. F. M. A. U. (2023).
Metalorganic chemical vapor deposition of ultrawide bandgap (Al
x
Ga
1-x
)
2
O
3
for next generation power electronics
[Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1689886516141118
APA Style (7th edition)
Bhuiyan, A F M Anhar Uddin.
Metalorganic chemical vapor deposition of ultrawide bandgap (Al
x
Ga
1-x
)
2
O
3
for next generation power electronics.
2023. Ohio State University, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=osu1689886516141118.
MLA Style (8th edition)
Bhuiyan, A F M Anhar Uddin. "Metalorganic chemical vapor deposition of ultrawide bandgap (Al
x
Ga
1-x
)
2
O
3
for next generation power electronics." Doctoral dissertation, Ohio State University, 2023. http://rave.ohiolink.edu/etdc/view?acc_num=osu1689886516141118
Chicago Manual of Style (17th edition)
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Document number:
osu1689886516141118
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© 2023, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.