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Zixuan Feng Dissertation-Final-0719.pdf (4.92 MB)

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Chemical vapor deposition of thin-film β-Ga2O3: an ultrawide bandgap semiconductor for next generation power electronics

Feng, Zixuan
http://rave.ohiolink.edu/etdc/view?acc_num=osu1626774853496559

Abstract Details

2021, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
This dissertation focuses on the development of chemical vapor deposition (CVD) of β-Ga2O3, an ultra-wide bandgap (UWBG) semiconductor representing one of the most promising semiconducting materials for next generation power electronics. Here, two types of CVD thin film deposition techniques were investigated, including the metalorganic chemical vapor deposition (MOCVD) and the low pressure chemical vapor deposition (LPCVD) methods. The main goal of this work aims to establish the fundamental understanding of this emerging UWBG semiconductor material through comprehensive mapping of the growth parameters combined with extensive material characterization. β-Ga2O3, with an ultra-wide bandgap of 4.5-4.9 eV and capability of n-doping, promises its applications for high power electronics. β-Ga2O3 is predicted to have a high breakdown field (~ 8 MV/cm) with room temperature mobility of ~200 cm2/Vs. The Baliga figure of merit (BFOM) of β-Ga2O3 for power electronics is predicted to be 2 to 3 times higher than that of GaN and SiC. One key advantage for β-Ga2O3 is from its availability of high quality and scalable native substrates synthesized via melt growth methods, which is critical to large-scale production with low cost. Thus, this UWBG material has great potential for future generation high power electronics as well as deep ultraviolet optoelectronics. The MOCVD growth window was explored for β-Ga2O3 thin films grown on native Ga2O3 substrates. Group IV Si was identified as an effective n-type dopant with a wide doping range from 1016-1020 cm-3. Under optimized growth conditions, β-Ga2O3 thin films grown on semi-insulating Fe-doped (010) Ga2O3 substrates demonstrated superior room temperature carrier mobilities of 184 and 194 cm2/V·s with and without intentional Si doping at charge concentration of 2.7×1016 cm-3 and 8.5×1015 cm-3, respectively. Temperature-dependent Hall measurements revealed a peak mobility of ~ 9500 cm2/V·s with extremely low compensation concentration at high-1014 cm-3, indicating high material quality with high purity of the MOCVD grown β-Ga2O3 thin films. The results from this work establish the great promise of this UWBG material for future power electronics which require low controllable doping. Built upon the MOCVD development of high quality β-Ga2O3 thin films, in-situ Mg doping of β-Ga2O3 thin films was successfully demonstrated with electrically insulating characteristics. The diffusion characteristics of Mg acceptor in MOCVD β-Ga2O3 were analyzed within a wide growth temperature range. The demonstration of in-situ Mg-doping in MOCVD β-Ga2O3 can provide new routes for high-performance device design and device fabrication. For the development of LPCVD β-Ga2O3 thin films, both homo- and hetero-epitaxy were comprehensively investigated. Key growth parameters that affect growth rate and transport characteristics were identified. The understanding of mechanism of gas phase reaction in LPCVD β-Ga2O3 leads to controllable growth of thin films with a wide range of growth rate and superior transport properties. High temperature LPCVD (HT-LPCVD) β-Ga2O3 homoepitaxy at 1050 ֯C has achieved high quality thin films with room temperature mobilities comparable to those grown by MOCVD. HT-LPCVD β-Ga2O3 heteroepitaxy on off-axis sapphire substrates has demonstrated mobility values of ~ 120-130 cm2/Vs.
Hongping Zhao (Advisor)
Steven Ringel (Committee Member)
Siddharth Rajan (Committee Member)
Hwang Jinwoo (Committee Member)
Patrick Woodward (Committee Member)
151 p.
Electrical Engineering; Materials Science
Ultrawide bandgap semiconductor; Ga2O3; oxide semiconductor; thin film epitaxy; metalorganic chemical vapor deposition; low pressure chemical vapor deposition;

Recommended Citations

Citations

  • Feng, Z. (2021). Chemical vapor deposition of thin-film β-Ga2O3: an ultrawide bandgap semiconductor for next generation power electronics [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1626774853496559

    APA Style (7th edition)

  • Feng, Zixuan. Chemical vapor deposition of thin-film β-Ga2O3: an ultrawide bandgap semiconductor for next generation power electronics. 2021. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1626774853496559.

    MLA Style (8th edition)

  • Feng, Zixuan. "Chemical vapor deposition of thin-film β-Ga2O3: an ultrawide bandgap semiconductor for next generation power electronics." Doctoral dissertation, Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1626774853496559

    Chicago Manual of Style (17th edition)

osu1626774853496559
318
© 2021, some rights reserved.Creative Commons License Chemical vapor deposition of thin-film β-Ga2O3: an ultrawide bandgap semiconductor for next generation power electronics by Zixuan Feng is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.