Exploring heteroepitaxial growth and electrical properties of α-Ga2O3 films on differently oriented sapphire substrates

Wei Wang; Shudong Hu; Zilong Wang; Kaisen Liu; Jinfu Zhang; Simiao Wu; Yuxia Yang; Ning Xia; Wenrui Zhang; Jichun Ye

doi:10.1088/1674-4926/44/6/062802

J. Semicond. > 2023, Volume 44 > Issue 6 > 062802

ARTICLES

Exploring heteroepitaxial growth and electrical properties of α-Ga₂O₃ films on differently oriented sapphire substrates

Wei Wang^{1, 2}, Shudong Hu¹, Zilong Wang¹, Kaisen Liu¹, Jinfu Zhang¹, Simiao Wu¹, Yuxia Yang¹, Ning Xia³, Wenrui Zhang^{1, 4,} and Jichun Ye^{1, 4,}

+ Author Affiliations

1. Zhejiang Provincial Engineering Research Center of Energy Optoelectronic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
2. The Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211, China
3. Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311200, China
4. Yongjiang Laboratory, Ningbo 315201, China

Author Bio:

is a M.S. candidate under the supervision of Dr. Wenrui Zhang at Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences. His research focuses on gallium oxide thin film growth and electronic devices.

received his Ph.D. degree at Texas A&M University in 2015. He is a professor at Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences. His research interest is wide bandgap semiconductors and microelectronic devices.

received his Ph.D. degree at University of California, Davis in 2005. He is a professor and the deputy director of the Institute of New Energy Technology affiliated with Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences. His main research areas include the development of solar cells and wide bandgap semiconductors.

Corresponding author: Wenrui Zhang, zhangwenrui@nimte.ac.cn; Jichun Ye, jichun.ye@nimte.ac.cn

DOI: 10.1088/1674-4926/44/6/062802

Abstract: This study explores the epitaxial relationship and electrical properties of α-Ga₂O₃ thin films deposited on a-plane, m-plane, and r-plane sapphire substrates. We characterize the thin films by X-ray diffraction and Raman spectroscopy, and elucidate thin film epitaxial relationships with the underlying sapphire substrates. The oxygen vacancy concentration of α-Ga₂O₃ thin films on m-plane and r-plane sapphire substrates are higher than α-Ga₂O₃ thin film on a-plane sapphire substrates. All three thin films have a high transmission of over 80% in the visible and near-ultraviolet regions, and their optical bandgaps stay around 5.02–5.16 eV. Hall measurements show that the α-Ga₂O₃ thin film grown on r-plane sapphire has the highest conductivity of 2.71 S/cm, which is at least 90 times higher than the film on a-plane sapphire. A similar orientation-dependence is seen in their activation energy as revealed by temperature-dependent conductivity measurements, with 0.266, 0.079, and 0.075 eV for the film on a-, m-, r-plane, respectively. The origin of the distinct transport behavior of films on differently oriented substrates is suggested to relate with the distinct evolution of oxygen vacancies at differently oriented substrates. This study provides insights for the substrate selection when growing α-Ga₂O₃ films with tunable transport properties.

Key words: gallium oxide, thin film epitaxy, orientation, oxygen vacancy, electrical properties

References

[1]	Konishi K, Goto K, Murakami H, et al. 1-kV vertical Ga₂O₃ field-plated Schottky barrier diodes. Appl Phys Lett, 2017, 110, 103506 doi: 10.1063/1.4977857
[2]	Hu Z Z, Zhou H, Feng Q, et al. Field-plated lateral β-Ga₂O₃ Schottky barrier diode with high reverse blocking voltage of more than 3 kV and high DC power figure-of-merit of 500 MW/cm². IEEE Electron Device Lett, 2018, 39, 1564 doi: 10.1109/LED.2018.2868444
[3]	Hao W B, He Q M, Zhou X Z, et al. 2.6 kV NiO/Ga₂O₃ heterojunction diode with superior high-temperature voltage blocking capability. 2022 IEEE 34th International Symposium on Power Semiconductor Devices and ICs (ISPSD), 2022, 105 doi: 10.1109/ISPSD49238.2022.9813680
[4]	Gong H H, Chen X H, Xu Y, et al. A 1.86-kV double-layered NiO/β-Ga₂O₃ vertical p–n heterojunction diode. Appl Phys Lett, 2020, 117, 022104 doi: 10.1063/5.0010052
[5]	Zhou X Z, Ma Y J, Xu G W, et al. Enhancement-mode β-Ga₂O₃ U-shaped gate trench vertical MOSFET realized by oxygen annealing. Appl Phys Lett, 2022, 121, 223501 doi: 10.1063/5.0130292
[6]	Moser N, McCandless J, Crespo A, et al. Ge-doped β-Ga₂O₃ MOSFETs. IEEE Electron Device Lett, 2017, 38, 775 doi: 10.1109/LED.2017.2697359
[7]	Jinno R, Chang C S, Onuma T, et al. Crystal orientation dictated epitaxy of ultrawide-bandgap 5.4- to 8.6-eV α-(AlGa)₂O₃ on m-plane sapphire. Sci Adv, 2021, 7, eabd5891 doi: 10.1126/sciadv.abd5891
[8]	Kracht M, Karg A, Feneberg M, et al. Anisotropic optical properties of metastable (011-2) α–Ga₂O₃ grown by plasma-assisted molecular beam epitaxy. Phys Rev Applied, 2018, 10, 024047 doi: 10.1103/PhysRevApplied.10.024047
[9]	Wu Z Y, Jiang Z X, Song P Y, et al. Nanowire-seeded growth of single-crystalline (010) β-Ga₂ O₃ nanosheets with high field-effect electron mobility and on/off current ratio. Small, 2019, 15, e1900580 doi: 10.1002/smll.201900580
[10]	Zhang W R, Zhang J G, Chen L, et al. Non-equilibrium epitaxy of metastable polymorphs of ultrawide-bandgap gallium oxide. Appl Phys Lett, 2022, 120, 072101 doi: 10.1063/5.0078752
[11]	Zhang J G, Wang W, Wu S M, et al. Exploratory phase stabilization in heteroepitaxial gallium oxide films by pulsed laser deposition. J Alloys Compd, 2023, 935, 168123 doi: 10.1016/j.jallcom.2022.168123
[12]	Wu C, Guo D Y, Zhang L Y, et al. Systematic investigation of the growth kinetics of β-Ga₂O₃ epilayer by plasma enhanced chemical vapor deposition. Appl Phys Lett, 2020, 116, 072102 doi: 10.1063/1.5142196
[13]	Wang W, Yuan Q L, Han D Y, et al. High-temperature deep ultraviolet photodetector based on a crystalline Ga₂O₃-diamond heterostructure. IEEE Electron Device Lett, 2022, 43, 2121 doi: 10.1109/LED.2022.3214981
[14]	Zhang Y B, Zheng J, Ma P P, et al. Growth and characterization of β-Ga₂O₃ thin films grown on off-angled Al₂O₃ substrates by metal-organic chemical vapor deposition. J Semicond, 2022, 43, 092801 doi: 10.1088/1674-4926/43/9/092801
[15]	Sun H D, Li K H, Torres Castanedo C G, et al. HCl flow-induced phase change of α-, β-, and ε-Ga₂O₃ films grown by MOCVD. Cryst Growth Des, 2018, 18, 2370 doi: 10.1021/acs.cgd.7b01791
[16]	Hou X H, Sun H D, Long S B, et al. Ultrahigh-performance solar-blind photodetector based on α-phase-dominated Ga₂O₃ film with record low dark current of 81 fA. IEEE Electron Device Lett, 2019, 40, 1483 doi: 10.1109/LED.2019.2932140
[17]	Nakagomi S, Kokubun Y. Crystal orientation of β-Ga₂O₃ thin films formed on c-plane and a-plane sapphire substrate. J Cryst Growth, 2012, 349, 12 doi: 10.1016/j.jcrysgro.2012.04.006
[18]	Chen X H, Ren F F, Gu S L, et al. Review of gallium-oxide-based solar-blind ultraviolet photodetectors. Photon Res, 2019, 7, 381 doi: 10.1364/PRJ.7.000381
[19]	Marezio M, Remeika J P. Bond lengths in the α-Ga₂O₃ structure and the high-pressure phase of Ga_2−xFe_xO₃. J Chem Phys, 1967, 46, 1862 doi: 10.1063/1.1840945
[20]	Nakagomi S, Kaneko S, Kokubun Y. Crystal orientations of β-Ga₂O₃ thin films formed on m-plane and r-plane sapphire substrates. Phys Status Solidi B, 2015, 252, 612 doi: 10.1002/pssb.201451456
[21]	Cheng Y L, Xu Y, Li Z, et al. Heteroepitaxial growth of α-Ga₂O₃ thin films on a-, c- and r-plane sapphire substrates by low-cost mist-CVD method. J Alloys Compd, 2020, 831, 154776 doi: 10.1016/j.jallcom.2020.154776
[22]	Hu H Z, Wu C, Zhao N, et al. Epitaxial growth and solar-blind photoelectric characteristic of Ga₂O₃ film on various oriented sapphire substrates by plasma-enhanced chemical vapor deposition. Phys Status Solidi A, 2021, 218, 2100076 doi: 10.1002/pssa.202100076
[23]	Chikoidze E, Rogers D J, Teherani F H, et al. Puzzling robust 2D metallic conductivity in undoped β-Ga₂O₃ thin films. Mater Today Phys, 2019, 8, 10 doi: 10.1016/j.mtphys.2018.11.006
[24]	Ghosh K, Singisetti U. Electron mobility in monoclinic β-Ga₂O₃—Effect of plasmon-phonon coupling, anisotropy, and confinement. J Mater Res, 2017, 32, 4142 doi: 10.1557/jmr.2017.398
[25]	Hou X, Zhao X, Zhang Y, et al. High-performance harsh-environment-resistant GaO_X solar-blind photodetectors via defect and doping engineering. Adv Mater, 2022, 34, e2106923 doi: 10.1002/adma.202106923
[26]	Zhang T, Guan D G, Liu N T, et al. Room temperature fabrication and post-annealing treatment of amorphous Ga₂O₃ photodetectors for deep-ultraviolet light detection. Appl Phys Express, 2022, 15, 022007 doi: 10.35848/1882-0786/ac48d9
[27]	Xiang X Q, Li L H, Chen C, et al. Unintentional doping effect in Si-doped MOCVD β-Ga₂O₃ films: Shallow donor states. Sci China Mater, 2023, 66, 748 doi: 10.1007/s40843-022-2167-x
[28]	Qin Y, Li L H, Zhao X L, et al. Metal–semiconductor–metal ε-Ga₂O₃ solar-blind photodetectors with a record-high responsivity rejection ratio and their gain mechanism. ACS Photonics, 2020, 7, 812 doi: 10.1021/acsphotonics.9b01727
[29]	Waseem A, Ren Z J, Huang H C, et al. A review of recent progress in β-Ga₂O₃ epitaxial growth: Effect of substrate orientation and precursors in metal–organic chemical vapor deposition. Phys Status Solidi A, 2022, 2200616 doi: 10.1002/pssa.202200616
[30]	Liu N T, Zhang T, Chen L, et al. Fast-response amorphous Ga₂O₃ solar-blind ultraviolet photodetectors tuned by a polar AlN template. IEEE Electron Device Lett, 2022, 43, 68 doi: 10.1109/LED.2021.3132497
[31]	Cuscó R, Domènech-Amador N, Hatakeyama T, et al. Lattice dynamics of a mist-chemical vapor deposition-grown corundum-like Ga₂O₃ single crystal. J Appl Phys, 2015, 117, 185706 doi: 10.1063/1.4921060
[32]	Ma T C, Chen X H, Ren F F, et al. Heteroepitaxial growth of thick α-Ga₂O₃ film on sapphire (0001) by MIST-CVD technique. J Semicond, 2019, 40, 012804 doi: 10.1088/1674-4926/40/1/012804
[33]	Mazzolini P, Falkenstein A, Wouters C, et al. Substrate-orientation dependence of β-Ga₂O₃ (100), (010), (001), and (-201) homoepitaxy by indium-mediated metal-exchange catalyzed molecular beam epitaxy (MEXCAT-MBE). APL Mater, 2020, 8, 011107 doi: 10.1063/1.5135772
[34]	Yen C C, Huang T M, Chen P W, et al. Role of interfacial oxide in the preferred orientation of Ga₂O₃ on Si for deep ultraviolet photodetectors. ACS Omega, 2021, 6, 29149 doi: 10.1021/acsomega.1c04380
[35]	Tak B R, Dewan S, Goyal A, et al. Point defects induced work function modulation of β-Ga₂O₃. Appl Surf Sci, 2019, 465, 973 doi: 10.1016/j.apsusc.2018.09.236
[36]	Miller A, Abrahams E. Impurity conduction at low concentrations. Phys Rev, 1960, 120, 745 doi: 10.1103/PhysRev.120.745
[37]	Hajnal Z, Miró J, Kiss G, et al. Role of oxygen vacancy defect states in the n-type conduction of β-Ga₂O₃. J Appl Phys, 1999, 86, 3792 doi: 10.1063/1.371289
[38]	Zhang J Y, Shi J L, Qi D C, et al. Recent progress on the electronic structure, defect, and doping properties of Ga₂O₃. APL Mater, 2020, 8, 020906 doi: 10.1063/1.5142999

Fig. 1. (Color online) (a) Schematic diagram of various crystal planes in the corundom structure. (b) The lattice mismatch between different crystal planes α-Ga₂O₃ films and corresponding sapphire substrates.

DownLoad: Full-Size Img PowerPoint

Fig. 2. (Color online) (a) XRD θ–2θ full scans of α-Ga₂O₃ thin films grown on a-plane, m-plane, and r-plane sapphire substrates. (b) XRD $\phi $-scans of ($ \text{30}\bar{\text{3}}\text{0} $) plane, ($\text{02}\bar{\text{2}}\text{4}$) plane, and ($\text{11}\bar{\text{2}}\text{0} $) plane of corresponding α-Ga₂O₃ films and the underlying sapphire, respectively. (c) Raman scattering spectra of α-Ga₂O₃ thin films grown on a-plane, m-plane, and r-plane sapphire substrates. (d) XRD rocking curves around the α-Ga₂O₃ ($\text{11}\bar{\text{2}}\text{0} $) peak grown on a-plane sapphire, α-Ga₂O₃ ($\text{30}\bar{\text{3}}\text{0} $) peak grown on m-plane sapphire, and α-Ga₂O₃ ($\text{02}\bar{\text{2}}\text{4} $) peak grown on r-plane sapphire.

DownLoad: Full-Size Img PowerPoint

Fig. 3. (Color online) Schematic of growth relation of α-Ga₂O₃ grown on (a) a-plane, (b) m-plane, and (c) r-plane sapphire substrates by PLD.

DownLoad: Full-Size Img PowerPoint

Fig. 4. (Color online) XPS spectra of O 1s peak of α-Ga₂O₃ films grown on (a) a-plane, (b) m-plane, and (c) r-plane sapphire substrates.

DownLoad: Full-Size Img PowerPoint

Fig. 5. (Color online) (a) Transmittance spectra and (b) Tauc plot of the a-plane, m-plane, and r-plane α-Ga₂O₃ thin films grown on various plane sapphire substrates.

DownLoad: Full-Size Img PowerPoint

Fig. 6. (Color online) Fitting plots of temperature-dependent resistance deriving the activation energy for a-plane, m-plane, and r-plane α-Ga₂O₃ thin films.

DownLoad: Full-Size Img PowerPoint

Table 1. Film thicknesses, conductivities, mobilities, and carrier concentrations for α-Ga₂O₃ thin films grown on a-, c- and r-plane sapphire substrates.

Substrate	Thickness (nm)	σ (S/cm)	μ (cm²/(V·s))	n (10¹⁷ cm⁻³)
a-sapphire	302	Exceed test limit (<0.03)	–	–
m-sapphire	280	0.29	12.2	1.45
r-sapphire	273	2.71	1.35	125

DownLoad: CSV

[1]	Konishi K, Goto K, Murakami H, et al. 1-kV vertical Ga₂O₃ field-plated Schottky barrier diodes. Appl Phys Lett, 2017, 110, 103506 doi: 10.1063/1.4977857
[2]	Hu Z Z, Zhou H, Feng Q, et al. Field-plated lateral β-Ga₂O₃ Schottky barrier diode with high reverse blocking voltage of more than 3 kV and high DC power figure-of-merit of 500 MW/cm². IEEE Electron Device Lett, 2018, 39, 1564 doi: 10.1109/LED.2018.2868444
[3]	Hao W B, He Q M, Zhou X Z, et al. 2.6 kV NiO/Ga₂O₃ heterojunction diode with superior high-temperature voltage blocking capability. 2022 IEEE 34th International Symposium on Power Semiconductor Devices and ICs (ISPSD), 2022, 105 doi: 10.1109/ISPSD49238.2022.9813680
[4]	Gong H H, Chen X H, Xu Y, et al. A 1.86-kV double-layered NiO/β-Ga₂O₃ vertical p–n heterojunction diode. Appl Phys Lett, 2020, 117, 022104 doi: 10.1063/5.0010052
[5]	Zhou X Z, Ma Y J, Xu G W, et al. Enhancement-mode β-Ga₂O₃ U-shaped gate trench vertical MOSFET realized by oxygen annealing. Appl Phys Lett, 2022, 121, 223501 doi: 10.1063/5.0130292
[6]	Moser N, McCandless J, Crespo A, et al. Ge-doped β-Ga₂O₃ MOSFETs. IEEE Electron Device Lett, 2017, 38, 775 doi: 10.1109/LED.2017.2697359
[7]	Jinno R, Chang C S, Onuma T, et al. Crystal orientation dictated epitaxy of ultrawide-bandgap 5.4- to 8.6-eV α-(AlGa)₂O₃ on m-plane sapphire. Sci Adv, 2021, 7, eabd5891 doi: 10.1126/sciadv.abd5891
[8]	Kracht M, Karg A, Feneberg M, et al. Anisotropic optical properties of metastable (011-2) α–Ga₂O₃ grown by plasma-assisted molecular beam epitaxy. Phys Rev Applied, 2018, 10, 024047 doi: 10.1103/PhysRevApplied.10.024047
[9]	Wu Z Y, Jiang Z X, Song P Y, et al. Nanowire-seeded growth of single-crystalline (010) β-Ga₂ O₃ nanosheets with high field-effect electron mobility and on/off current ratio. Small, 2019, 15, e1900580 doi: 10.1002/smll.201900580
[10]	Zhang W R, Zhang J G, Chen L, et al. Non-equilibrium epitaxy of metastable polymorphs of ultrawide-bandgap gallium oxide. Appl Phys Lett, 2022, 120, 072101 doi: 10.1063/5.0078752
[11]	Zhang J G, Wang W, Wu S M, et al. Exploratory phase stabilization in heteroepitaxial gallium oxide films by pulsed laser deposition. J Alloys Compd, 2023, 935, 168123 doi: 10.1016/j.jallcom.2022.168123
[12]	Wu C, Guo D Y, Zhang L Y, et al. Systematic investigation of the growth kinetics of β-Ga₂O₃ epilayer by plasma enhanced chemical vapor deposition. Appl Phys Lett, 2020, 116, 072102 doi: 10.1063/1.5142196
[13]	Wang W, Yuan Q L, Han D Y, et al. High-temperature deep ultraviolet photodetector based on a crystalline Ga₂O₃-diamond heterostructure. IEEE Electron Device Lett, 2022, 43, 2121 doi: 10.1109/LED.2022.3214981
[14]	Zhang Y B, Zheng J, Ma P P, et al. Growth and characterization of β-Ga₂O₃ thin films grown on off-angled Al₂O₃ substrates by metal-organic chemical vapor deposition. J Semicond, 2022, 43, 092801 doi: 10.1088/1674-4926/43/9/092801
[15]	Sun H D, Li K H, Torres Castanedo C G, et al. HCl flow-induced phase change of α-, β-, and ε-Ga₂O₃ films grown by MOCVD. Cryst Growth Des, 2018, 18, 2370 doi: 10.1021/acs.cgd.7b01791
[16]	Hou X H, Sun H D, Long S B, et al. Ultrahigh-performance solar-blind photodetector based on α-phase-dominated Ga₂O₃ film with record low dark current of 81 fA. IEEE Electron Device Lett, 2019, 40, 1483 doi: 10.1109/LED.2019.2932140
[17]	Nakagomi S, Kokubun Y. Crystal orientation of β-Ga₂O₃ thin films formed on c-plane and a-plane sapphire substrate. J Cryst Growth, 2012, 349, 12 doi: 10.1016/j.jcrysgro.2012.04.006
[18]	Chen X H, Ren F F, Gu S L, et al. Review of gallium-oxide-based solar-blind ultraviolet photodetectors. Photon Res, 2019, 7, 381 doi: 10.1364/PRJ.7.000381
[19]	Marezio M, Remeika J P. Bond lengths in the α-Ga₂O₃ structure and the high-pressure phase of Ga_2−xFe_xO₃. J Chem Phys, 1967, 46, 1862 doi: 10.1063/1.1840945
[20]	Nakagomi S, Kaneko S, Kokubun Y. Crystal orientations of β-Ga₂O₃ thin films formed on m-plane and r-plane sapphire substrates. Phys Status Solidi B, 2015, 252, 612 doi: 10.1002/pssb.201451456
[21]	Cheng Y L, Xu Y, Li Z, et al. Heteroepitaxial growth of α-Ga₂O₃ thin films on a-, c- and r-plane sapphire substrates by low-cost mist-CVD method. J Alloys Compd, 2020, 831, 154776 doi: 10.1016/j.jallcom.2020.154776
[22]	Hu H Z, Wu C, Zhao N, et al. Epitaxial growth and solar-blind photoelectric characteristic of Ga₂O₃ film on various oriented sapphire substrates by plasma-enhanced chemical vapor deposition. Phys Status Solidi A, 2021, 218, 2100076 doi: 10.1002/pssa.202100076
[23]	Chikoidze E, Rogers D J, Teherani F H, et al. Puzzling robust 2D metallic conductivity in undoped β-Ga₂O₃ thin films. Mater Today Phys, 2019, 8, 10 doi: 10.1016/j.mtphys.2018.11.006
[24]	Ghosh K, Singisetti U. Electron mobility in monoclinic β-Ga₂O₃—Effect of plasmon-phonon coupling, anisotropy, and confinement. J Mater Res, 2017, 32, 4142 doi: 10.1557/jmr.2017.398
[25]	Hou X, Zhao X, Zhang Y, et al. High-performance harsh-environment-resistant GaO_X solar-blind photodetectors via defect and doping engineering. Adv Mater, 2022, 34, e2106923 doi: 10.1002/adma.202106923
[26]	Zhang T, Guan D G, Liu N T, et al. Room temperature fabrication and post-annealing treatment of amorphous Ga₂O₃ photodetectors for deep-ultraviolet light detection. Appl Phys Express, 2022, 15, 022007 doi: 10.35848/1882-0786/ac48d9
[27]	Xiang X Q, Li L H, Chen C, et al. Unintentional doping effect in Si-doped MOCVD β-Ga₂O₃ films: Shallow donor states. Sci China Mater, 2023, 66, 748 doi: 10.1007/s40843-022-2167-x
[28]	Qin Y, Li L H, Zhao X L, et al. Metal–semiconductor–metal ε-Ga₂O₃ solar-blind photodetectors with a record-high responsivity rejection ratio and their gain mechanism. ACS Photonics, 2020, 7, 812 doi: 10.1021/acsphotonics.9b01727
[29]	Waseem A, Ren Z J, Huang H C, et al. A review of recent progress in β-Ga₂O₃ epitaxial growth: Effect of substrate orientation and precursors in metal–organic chemical vapor deposition. Phys Status Solidi A, 2022, 2200616 doi: 10.1002/pssa.202200616
[30]	Liu N T, Zhang T, Chen L, et al. Fast-response amorphous Ga₂O₃ solar-blind ultraviolet photodetectors tuned by a polar AlN template. IEEE Electron Device Lett, 2022, 43, 68 doi: 10.1109/LED.2021.3132497
[31]	Cuscó R, Domènech-Amador N, Hatakeyama T, et al. Lattice dynamics of a mist-chemical vapor deposition-grown corundum-like Ga₂O₃ single crystal. J Appl Phys, 2015, 117, 185706 doi: 10.1063/1.4921060
[32]	Ma T C, Chen X H, Ren F F, et al. Heteroepitaxial growth of thick α-Ga₂O₃ film on sapphire (0001) by MIST-CVD technique. J Semicond, 2019, 40, 012804 doi: 10.1088/1674-4926/40/1/012804
[33]	Mazzolini P, Falkenstein A, Wouters C, et al. Substrate-orientation dependence of β-Ga₂O₃ (100), (010), (001), and (-201) homoepitaxy by indium-mediated metal-exchange catalyzed molecular beam epitaxy (MEXCAT-MBE). APL Mater, 2020, 8, 011107 doi: 10.1063/1.5135772
[34]	Yen C C, Huang T M, Chen P W, et al. Role of interfacial oxide in the preferred orientation of Ga₂O₃ on Si for deep ultraviolet photodetectors. ACS Omega, 2021, 6, 29149 doi: 10.1021/acsomega.1c04380
[35]	Tak B R, Dewan S, Goyal A, et al. Point defects induced work function modulation of β-Ga₂O₃. Appl Surf Sci, 2019, 465, 973 doi: 10.1016/j.apsusc.2018.09.236
[36]	Miller A, Abrahams E. Impurity conduction at low concentrations. Phys Rev, 1960, 120, 745 doi: 10.1103/PhysRev.120.745
[37]	Hajnal Z, Miró J, Kiss G, et al. Role of oxygen vacancy defect states in the n-type conduction of β-Ga₂O₃. J Appl Phys, 1999, 86, 3792 doi: 10.1063/1.371289
[38]	Zhang J Y, Shi J L, Qi D C, et al. Recent progress on the electronic structure, defect, and doping properties of Ga₂O₃. APL Mater, 2020, 8, 020906 doi: 10.1063/1.5142999

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Received: 28 December 2022 Revised: 03 February 2023 Online: Accepted Manuscript: 10 March 2023Uncorrected proof: 12 April 2023Corrected proof: 22 May 2023Published: 08 June 2023

Article Navigation > Journal of Semiconductors > 2023 > 44(6): 062802

Wei Wang, Shudong Hu, Zilong Wang, Kaisen Liu, Jinfu Zhang, Simiao Wu, Yuxia Yang, Ning Xia, Wenrui Zhang, Jichun Ye. Exploring heteroepitaxial growth and electrical properties of α-Ga2O3 films on differently oriented sapphire substrates[J]. Journal of Semiconductors, 2023, 44(6): 062802. doi: 10.1088/1674-4926/44/6/062802 ****Wei Wang, Shudong Hu, Zilong Wang, Kaisen Liu, Jinfu Zhang, Simiao Wu, Yuxia Yang, Ning Xia, Wenrui Zhang, Jichun Ye. 2023: Exploring heteroepitaxial growth and electrical properties of α-Ga2O3 films on differently oriented sapphire substrates. Journal of Semiconductors, 44(6): 062802. doi: 10.1088/1674-4926/44/6/062802

Citation:

Wei Wang, Shudong Hu, Zilong Wang, Kaisen Liu, Jinfu Zhang, Simiao Wu, Yuxia Yang, Ning Xia, Wenrui Zhang, Jichun Ye. 2023: Exploring heteroepitaxial growth and electrical properties of α-Ga₂O₃ films on differently oriented sapphire substrates. Journal of Semiconductors, 44(6): 062802. doi: 10.1088/1674-4926/44/6/062802

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Exploring heteroepitaxial growth and electrical properties of α-Ga₂O₃ films on differently oriented sapphire substrates

DOI: 10.1088/1674-4926/44/6/062802

1.
Zhejiang Provincial Engineering Research Center of Energy Optoelectronic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
2.
The Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211, China
3.
Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311200, China
4.
Yongjiang Laboratory, Ningbo 315201, China

More Information

Wei Wang：is a M.S. candidate under the supervision of Dr. Wenrui Zhang at Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences. His research focuses on gallium oxide thin film growth and electronic devices
Wenrui Zhang：received his Ph.D. degree at Texas A&M University in 2015. He is a professor at Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences. His research interest is wide bandgap semiconductors and microelectronic devices
Jichun Ye：received his Ph.D. degree at University of California, Davis in 2005. He is a professor and the deputy director of the Institute of New Energy Technology affiliated with Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences. His main research areas include the development of solar cells and wide bandgap semiconductors
Corresponding author: zhangwenrui@nimte.ac.cn; jichun.ye@nimte.ac.cn
Received Date: 2022-12-28
Revised Date: 2023-02-03

Available Online: 2023-03-10

Abstract

Abstract

This study explores the epitaxial relationship and electrical properties of α-Ga₂O₃ thin films deposited on a-plane, m-plane, and r-plane sapphire substrates. We characterize the thin films by X-ray diffraction and Raman spectroscopy, and elucidate thin film epitaxial relationships with the underlying sapphire substrates. The oxygen vacancy concentration of α-Ga₂O₃ thin films on m-plane and r-plane sapphire substrates are higher than α-Ga₂O₃ thin film on a-plane sapphire substrates. All three thin films have a high transmission of over 80% in the visible and near-ultraviolet regions, and their optical bandgaps stay around 5.02–5.16 eV. Hall measurements show that the α-Ga₂O₃ thin film grown on r-plane sapphire has the highest conductivity of 2.71 S/cm, which is at least 90 times higher than the film on a-plane sapphire. A similar orientation-dependence is seen in their activation energy as revealed by temperature-dependent conductivity measurements, with 0.266, 0.079, and 0.075 eV for the film on a-, m-, r-plane, respectively. The origin of the distinct transport behavior of films on differently oriented substrates is suggested to relate with the distinct evolution of oxygen vacancies at differently oriented substrates. This study provides insights for the substrate selection when growing α-Ga₂O₃ films with tunable transport properties.
- gallium oxide,
- thin film epitaxy,
- orientation,
- oxygen vacancy,
- electrical properties

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References(38)

References

[1]	Konishi K, Goto K, Murakami H, et al. 1-kV vertical Ga₂O₃ field-plated Schottky barrier diodes. Appl Phys Lett, 2017, 110, 103506 doi: 10.1063/1.4977857
[2]	Hu Z Z, Zhou H, Feng Q, et al. Field-plated lateral β-Ga₂O₃ Schottky barrier diode with high reverse blocking voltage of more than 3 kV and high DC power figure-of-merit of 500 MW/cm². IEEE Electron Device Lett, 2018, 39, 1564 doi: 10.1109/LED.2018.2868444
[3]	Hao W B, He Q M, Zhou X Z, et al. 2.6 kV NiO/Ga₂O₃ heterojunction diode with superior high-temperature voltage blocking capability. 2022 IEEE 34th International Symposium on Power Semiconductor Devices and ICs (ISPSD), 2022, 105 doi: 10.1109/ISPSD49238.2022.9813680
[4]	Gong H H, Chen X H, Xu Y, et al. A 1.86-kV double-layered NiO/β-Ga₂O₃ vertical p–n heterojunction diode. Appl Phys Lett, 2020, 117, 022104 doi: 10.1063/5.0010052
[5]	Zhou X Z, Ma Y J, Xu G W, et al. Enhancement-mode β-Ga₂O₃ U-shaped gate trench vertical MOSFET realized by oxygen annealing. Appl Phys Lett, 2022, 121, 223501 doi: 10.1063/5.0130292
[6]	Moser N, McCandless J, Crespo A, et al. Ge-doped β-Ga₂O₃ MOSFETs. IEEE Electron Device Lett, 2017, 38, 775 doi: 10.1109/LED.2017.2697359
[7]	Jinno R, Chang C S, Onuma T, et al. Crystal orientation dictated epitaxy of ultrawide-bandgap 5.4- to 8.6-eV α-(AlGa)₂O₃ on m-plane sapphire. Sci Adv, 2021, 7, eabd5891 doi: 10.1126/sciadv.abd5891
[8]	Kracht M, Karg A, Feneberg M, et al. Anisotropic optical properties of metastable (011-2) α–Ga₂O₃ grown by plasma-assisted molecular beam epitaxy. Phys Rev Applied, 2018, 10, 024047 doi: 10.1103/PhysRevApplied.10.024047
[9]	Wu Z Y, Jiang Z X, Song P Y, et al. Nanowire-seeded growth of single-crystalline (010) β-Ga₂ O₃ nanosheets with high field-effect electron mobility and on/off current ratio. Small, 2019, 15, e1900580 doi: 10.1002/smll.201900580
[10]	Zhang W R, Zhang J G, Chen L, et al. Non-equilibrium epitaxy of metastable polymorphs of ultrawide-bandgap gallium oxide. Appl Phys Lett, 2022, 120, 072101 doi: 10.1063/5.0078752
[11]	Zhang J G, Wang W, Wu S M, et al. Exploratory phase stabilization in heteroepitaxial gallium oxide films by pulsed laser deposition. J Alloys Compd, 2023, 935, 168123 doi: 10.1016/j.jallcom.2022.168123
[12]	Wu C, Guo D Y, Zhang L Y, et al. Systematic investigation of the growth kinetics of β-Ga₂O₃ epilayer by plasma enhanced chemical vapor deposition. Appl Phys Lett, 2020, 116, 072102 doi: 10.1063/1.5142196
[13]	Wang W, Yuan Q L, Han D Y, et al. High-temperature deep ultraviolet photodetector based on a crystalline Ga₂O₃-diamond heterostructure. IEEE Electron Device Lett, 2022, 43, 2121 doi: 10.1109/LED.2022.3214981
[14]	Zhang Y B, Zheng J, Ma P P, et al. Growth and characterization of β-Ga₂O₃ thin films grown on off-angled Al₂O₃ substrates by metal-organic chemical vapor deposition. J Semicond, 2022, 43, 092801 doi: 10.1088/1674-4926/43/9/092801
[15]	Sun H D, Li K H, Torres Castanedo C G, et al. HCl flow-induced phase change of α-, β-, and ε-Ga₂O₃ films grown by MOCVD. Cryst Growth Des, 2018, 18, 2370 doi: 10.1021/acs.cgd.7b01791
[16]	Hou X H, Sun H D, Long S B, et al. Ultrahigh-performance solar-blind photodetector based on α-phase-dominated Ga₂O₃ film with record low dark current of 81 fA. IEEE Electron Device Lett, 2019, 40, 1483 doi: 10.1109/LED.2019.2932140
[17]	Nakagomi S, Kokubun Y. Crystal orientation of β-Ga₂O₃ thin films formed on c-plane and a-plane sapphire substrate. J Cryst Growth, 2012, 349, 12 doi: 10.1016/j.jcrysgro.2012.04.006
[18]	Chen X H, Ren F F, Gu S L, et al. Review of gallium-oxide-based solar-blind ultraviolet photodetectors. Photon Res, 2019, 7, 381 doi: 10.1364/PRJ.7.000381
[19]	Marezio M, Remeika J P. Bond lengths in the α-Ga₂O₃ structure and the high-pressure phase of Ga_2−xFe_xO₃. J Chem Phys, 1967, 46, 1862 doi: 10.1063/1.1840945
[20]	Nakagomi S, Kaneko S, Kokubun Y. Crystal orientations of β-Ga₂O₃ thin films formed on m-plane and r-plane sapphire substrates. Phys Status Solidi B, 2015, 252, 612 doi: 10.1002/pssb.201451456
[21]	Cheng Y L, Xu Y, Li Z, et al. Heteroepitaxial growth of α-Ga₂O₃ thin films on a-, c- and r-plane sapphire substrates by low-cost mist-CVD method. J Alloys Compd, 2020, 831, 154776 doi: 10.1016/j.jallcom.2020.154776
[22]	Hu H Z, Wu C, Zhao N, et al. Epitaxial growth and solar-blind photoelectric characteristic of Ga₂O₃ film on various oriented sapphire substrates by plasma-enhanced chemical vapor deposition. Phys Status Solidi A, 2021, 218, 2100076 doi: 10.1002/pssa.202100076
[23]	Chikoidze E, Rogers D J, Teherani F H, et al. Puzzling robust 2D metallic conductivity in undoped β-Ga₂O₃ thin films. Mater Today Phys, 2019, 8, 10 doi: 10.1016/j.mtphys.2018.11.006
[24]	Ghosh K, Singisetti U. Electron mobility in monoclinic β-Ga₂O₃—Effect of plasmon-phonon coupling, anisotropy, and confinement. J Mater Res, 2017, 32, 4142 doi: 10.1557/jmr.2017.398
[25]	Hou X, Zhao X, Zhang Y, et al. High-performance harsh-environment-resistant GaO_X solar-blind photodetectors via defect and doping engineering. Adv Mater, 2022, 34, e2106923 doi: 10.1002/adma.202106923
[26]	Zhang T, Guan D G, Liu N T, et al. Room temperature fabrication and post-annealing treatment of amorphous Ga₂O₃ photodetectors for deep-ultraviolet light detection. Appl Phys Express, 2022, 15, 022007 doi: 10.35848/1882-0786/ac48d9
[27]	Xiang X Q, Li L H, Chen C, et al. Unintentional doping effect in Si-doped MOCVD β-Ga₂O₃ films: Shallow donor states. Sci China Mater, 2023, 66, 748 doi: 10.1007/s40843-022-2167-x
[28]	Qin Y, Li L H, Zhao X L, et al. Metal–semiconductor–metal ε-Ga₂O₃ solar-blind photodetectors with a record-high responsivity rejection ratio and their gain mechanism. ACS Photonics, 2020, 7, 812 doi: 10.1021/acsphotonics.9b01727
[29]	Waseem A, Ren Z J, Huang H C, et al. A review of recent progress in β-Ga₂O₃ epitaxial growth: Effect of substrate orientation and precursors in metal–organic chemical vapor deposition. Phys Status Solidi A, 2022, 2200616 doi: 10.1002/pssa.202200616
[30]	Liu N T, Zhang T, Chen L, et al. Fast-response amorphous Ga₂O₃ solar-blind ultraviolet photodetectors tuned by a polar AlN template. IEEE Electron Device Lett, 2022, 43, 68 doi: 10.1109/LED.2021.3132497
[31]	Cuscó R, Domènech-Amador N, Hatakeyama T, et al. Lattice dynamics of a mist-chemical vapor deposition-grown corundum-like Ga₂O₃ single crystal. J Appl Phys, 2015, 117, 185706 doi: 10.1063/1.4921060
[32]	Ma T C, Chen X H, Ren F F, et al. Heteroepitaxial growth of thick α-Ga₂O₃ film on sapphire (0001) by MIST-CVD technique. J Semicond, 2019, 40, 012804 doi: 10.1088/1674-4926/40/1/012804
[33]	Mazzolini P, Falkenstein A, Wouters C, et al. Substrate-orientation dependence of β-Ga₂O₃ (100), (010), (001), and (-201) homoepitaxy by indium-mediated metal-exchange catalyzed molecular beam epitaxy (MEXCAT-MBE). APL Mater, 2020, 8, 011107 doi: 10.1063/1.5135772
[34]	Yen C C, Huang T M, Chen P W, et al. Role of interfacial oxide in the preferred orientation of Ga₂O₃ on Si for deep ultraviolet photodetectors. ACS Omega, 2021, 6, 29149 doi: 10.1021/acsomega.1c04380
[35]	Tak B R, Dewan S, Goyal A, et al. Point defects induced work function modulation of β-Ga₂O₃. Appl Surf Sci, 2019, 465, 973 doi: 10.1016/j.apsusc.2018.09.236
[36]	Miller A, Abrahams E. Impurity conduction at low concentrations. Phys Rev, 1960, 120, 745 doi: 10.1103/PhysRev.120.745
[37]	Hajnal Z, Miró J, Kiss G, et al. Role of oxygen vacancy defect states in the n-type conduction of β-Ga₂O₃. J Appl Phys, 1999, 86, 3792 doi: 10.1063/1.371289
[38]	Zhang J Y, Shi J L, Qi D C, et al. Recent progress on the electronic structure, defect, and doping properties of Ga₂O₃. APL Mater, 2020, 8, 020906 doi: 10.1063/1.5142999

Exploring heteroepitaxial growth and electrical properties of α-Ga₂O₃ films on differently oriented sapphire substrates

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Exploring heteroepitaxial growth and electrical properties of α-Ga₂O₃ films on differently oriented sapphire substrates

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Exploring heteroepitaxial growth and electrical properties of α-Ga₂O₃ films on differently oriented sapphire substrates

Exploring heteroepitaxial growth and electrical properties of α-Ga₂O₃ films on differently oriented sapphire substrates