Monika, Sadia K.
III- Nitride Enhancement Mode Device.
Degree: MS, Electrical and Computer Engineering, 2017, The Ohio State University
GaN is a promising material for energy efficient high
power switching applications due to its wide bandgap, and high
critical field. However, for such applications normally off devices
with high positive threshold voltage and low off-state current is
desirable. In this thesis, first, we investigated the effects of
different scattering mechanisms on the low field mobility of GaN
MOSFET. We found that, unlike AlGaN/GaN HEMTs, where mobility is
limited by phonon scattering, mobility in GaN MOSFET is limited by
interface ionized impurity scattering and surface roughness
scattering. Next, we investigate the effect of different process
steps, namely, O2 plasma treatment, post dielectric anneal(PDA),
and post metal anneal(PMA), on the threshold voltage, hysteresis,
and mobility of Al2O3/GaN MOSFETs. Our study reveals that (a) lower
hysteresis can be achieved by high temperature PDA in the presence
of O2 plasma and PMA treatment, (b) large positive threshold
voltage can be achieved with high temperature PDA and PMA treatment
in absence of O2 plasma, and (c) high mobility can be achieved with
only high temperature PMA treatment without O2 plasma and PDA
treatment. Using our optimized process condition we achieved GaN
MOSFET with 1.5 V threshold, 0.1 V hysteresis, 225 cm2V-1s-1
mobility, 67 mV/dec subthreshold swing, and 1010 on-off ratio. We
also investigated the potential of AlON as a gate dielectric in GaN
MOSFET. It is found that AlON can increase the threshold voltage in
both HEMTs and MOSFET structures, most probably due to behavior of
nitrogen atoms as acceptor like states. We demonstrate a 5 V, and
1.5 V shift in HEMT, and MOSFET structure using AlON as gate
Advisors/Committee Members: Siddharth, Rajan (Advisor).
Subjects/Keywords: Electrical Engineering; GaN MOSFET, E-mode, GIT, Power Device, Positive threshold
voltage, Mobility, Hysteresis, Subthreshold slope, Normally off
to Zotero / EndNote / Reference
APA (6th Edition):
Monika, S. K. (2017). III- Nitride Enhancement Mode Device. (Masters Thesis). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1483535296785214
Chicago Manual of Style (16th Edition):
Monika, Sadia K. “III- Nitride Enhancement Mode Device.” 2017. Masters Thesis, The Ohio State University. Accessed January 22, 2018.
MLA Handbook (7th Edition):
Monika, Sadia K. “III- Nitride Enhancement Mode Device.” 2017. Web. 22 Jan 2018.
Monika SK. III- Nitride Enhancement Mode Device. [Internet] [Masters thesis]. The Ohio State University; 2017. [cited 2018 Jan 22].
Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1483535296785214.
Council of Science Editors:
Monika SK. III- Nitride Enhancement Mode Device. [Masters Thesis]. The Ohio State University; 2017. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1483535296785214