Growth of N-polar GaN on vicinal sapphire substrate by metal organic chemical vapor deposition

Zhong, C.; Zhang, Guoyi

doi:10.1007/s12598-013-0163-5

Cited by 9 publications

(9 citation statements)

References 15 publications

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“…This is because the oxygen atoms of (0001) plane of sapphire substrate has a similar atomic arrangement as the (−201) equivalent plane of β‐Ga 2 O 3 . It has been reported previously for III‐nitride epitaxial films that the full width at half maximum (FWHM) values of the symmetric and asymmetric diffraction peaks are associated with screw and edge dislocations respectively . In this study, we have performed the XRD rocking curve measurements for both symmetric (−402) and asymmetric (−202) diffraction peaks.…”

Section: Resultsmentioning

confidence: 90%

Towards High‐Mobility Heteroepitaxial β‐Ga₂O₃ on Sapphire − Dependence on The Substrate Off‐Axis Angle

Rafique

Han

Neal

et al. 2017

Physica Status Solidi (a)

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This paper presents the heteroepitaxial growth of β‐Ga2O3 thin films on off‐axis (0001) c‐sapphire substrates by low pressure chemical vapor deposition (LPCVD). (−201) oriented β‐Ga2O3 thin films are grown using high purity metallic gallium (Ga) and oxygen (O2) as the precursors. N‐type conductivity in silicon doped β‐Ga2O3 thin films is demonstrated. It is found that the film crystalline quality, surface morphology, and electrical conductivity are remarkably sensitive to the off‐axis angles. X‐ray phi‐scan measurements of the β‐Ga2O3 film grown on on‐axis c‐sapphire indicate the presence of six in‐plane rotational domains due to the substrate symmetry. With the increase of off‐axis angle toward <11–20> of sapphire, one of the in‐plane orientations is strongly favored. The use of off‐axis substrate also reduced the X‐ray rocking curve full width at half maximum and increased the intensities of the Raman peaks. The best electrical properties of the β‐Ga2O3 film are exhibited by the film grown on 6° off‐axis c‐sapphire. The room temperature electron Hall mobility was 106.6 cm2 V−1 s−1 with an n‐type carrier concentration of 4.83 × 1017 cm−3. The results from this study demonstrate high electrical quality β‐Ga2O3 thin films grown on off‐axis c‐sapphire substrates, which are promising for high power electronic and short wavelength optoelectronic device applications.

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Section: Resultsmentioning

confidence: 90%

Towards High‐Mobility Heteroepitaxial β‐Ga₂O₃ on Sapphire − Dependence on The Substrate Off‐Axis Angle

Rafique

Han

Neal

et al. 2017

Physica Status Solidi (a)

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“…The XRD rocking curve ω scan of the commercial substrate (Figure a) shows a sharp narrow peak with a full width at half-maximum (FWHM) of 0.018° (64.8 arcsec). The FWHM of the XRD rocking curves of the films grown on 6° offcut substrates (while being significantly broader than the FWHM of the bulk β-Ga 2 O 3 ) consistently exhibited lower values than those grown on 0° offcut substrates, which could indicate lower screw and edge dislocation densities. , …”

Section: Resultsmentioning

confidence: 88%

“…The FWHM of the XRD rocking curves of the films grown on 6°offcut substrates (while being significantly broader than the FWHM of the bulk β-Ga 2 O 3 ) consistently exhibited lower values than those grown on 0°offcut substrates, which could indicate lower screw and edge dislocation densities. 43,44 Additional qualitative assessment of the crystal quality of the films was made by performing Raman spectroscopy measurements. To assess the crystalline quality of the β-Ga 2 O 3 thin films, the FWHM of the A g (3) Raman peak 45 near 199.7 cm −1 was analyzed and also compared with the linewidth of the A g (3) peak of the bulk substrate (Figure 5a).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Thermal Conductivity of β-Phase Ga₂O₃ and (Al_xGa_1–_x)₂O₃ Heteroepitaxial Thin Films

Song

Ranga

Zhang

et al. 2021

ACS Appl. Mater. Interfaces

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Heteroepitaxy of β-phase gallium oxide (β-Ga 2 O 3 ) thin films on foreign substrates shows promise for the development of next-generation deep ultraviolet solar blind photodetectors and power electronic devices. In this work, the influences of the film thickness and crystallinity on the thermal conductivity of (2̅ 01)-oriented β-Ga 2 O 3 heteroepitaxial thin films were investigated. Unintentionally doped β-Ga 2 O 3 thin films were grown on c-plane sapphire substrates with off-axis angles of 0°and 6°toward ⟨112̅ 0⟩ via metal−organic vapor phase epitaxy (MOVPE) and low-pressure chemical vapor deposition. The surface morphology and crystal quality of the β-Ga 2 O 3 thin films were characterized using scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The thermal conductivities of the β-Ga 2 O 3 films were measured via time-domain thermoreflectance. The interface quality was studied using scanning transmission electron microscopy. The measured thermal conductivities of the submicron-thick β-Ga 2 O 3 thin films were relatively low as compared to the intrinsic bulk value. The measured thin film thermal conductivities were compared with the Debye−Callaway model incorporating phononic parameters derived from first-principles calculations. The comparison suggests that the reduction in the thin film thermal conductivity can be partially attributed to the enhanced phonon-boundary scattering when the film thickness decreases. They were found to be a strong function of not only the layer thickness but also the film quality, resulting from growth on substrates with different offcut angles. Growth of β-Ga 2 O 3 films on 6°offcut sapphire substrates was found to result in higher crystallinity and thermal conductivity than films grown on on-axis c-plane sapphire. However, the β-Ga 2 O 3 films grown on 6°offcut sapphire exhibit a lower thermal boundary conductance at the β-Ga 2 O 3 / sapphire heterointerface. In addition, the thermal conductivity of MOVPE-grown (2̅ 01)-oriented β-(Al x Ga 1−x ) 2 O 3 thin films with Al compositions ranging from 2% to 43% was characterized. Because of phonon-alloy disorder scattering, the β-(Al x Ga 1−x ) 2 O 3 films exhibit lower thermal conductivities (2.8−4.7 W/m•K) than the β-Ga 2 O 3 thin films. The dominance of the alloy disorder scattering in β-(Al x Ga 1−x ) 2 O 3 is further evidenced by the weak temperature dependence of the thermal conductivity. This work provides fundamental insight into the physical interactions that govern phonon transport within heteroepitaxially grown β-phase Ga 2 O 3 and (Al x Ga 1−x ) 2 O 3 thin films and lays the groundwork for the thermal modeling and design of β-Ga 2 O 3 electronic and optoelectronic devices.

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“…According to a study by Prasertsuk et al, the surface morphology of N‐polar GaN/AlGaN was varied by modifying the misorientation angle of the underlying sapphire . For N‐polar GaN on a sapphire substrate, it is known that a vicinal substrate is effective for improving the surface morphology of N‐polar GaN . Similarly, a vicinal substrate can be effective for improving the surface morphology of the N‐polar AlN layer as well.…”

Section: Introductionmentioning

confidence: 99%

“…[16] For N-polar GaN on a sapphire substrate, it is known that a vicinal substrate is effective for improving the surface morphology of N-polar GaN. [17] Similarly, a vicinal substrate can be effective for improving the surface morphology of the N-polar AlN layer as well. However, very few reports have been conducted relating to N-polar AlN growth on vicinal sapphire and SiC.…”

Section: Introductionmentioning

confidence: 99%

Growth of N‐Polar Aluminum Nitride on Vicinal Sapphire Substrates and Aluminum Nitride Bulk Substrates

Isono

Ito

Sakamoto

et al. 2020

Physica Status Solidi (b)

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Herein, nitrogen‐polar (N‐polar, (000‐1)) aluminum nitride (AlN) is grown on sapphire substrates with various misorientation angles through metal‐organic vapor phase epitaxy. Moreover, the effect of the sapphire substrates’ misorientation angle on the surface flatness and the crystal quality of N‐polar AlN is studied. The results demonstrate that the surface flatness of the AlN layer improves as the misorientation angle of the sapphire substrates increases. Further, the root mean square of the AlN layer significantly improves to a maximum of 1 nm, in the range of the misorientation angles between 2° and 4°, as compared with the misorientation angle of 0.2° of a conventional substrate. No deterioration in crystallinity is confirmed when an AlN layer is grown on an N‐polar AlN substrate under the same growth conditions as those for the sapphire substrates.

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Growth of N-polar GaN on vicinal sapphire substrate by metal organic chemical vapor deposition

Cited by 9 publications

References 15 publications

Towards High‐Mobility Heteroepitaxial β‐Ga₂O₃ on Sapphire − Dependence on The Substrate Off‐Axis Angle

Towards High‐Mobility Heteroepitaxial β‐Ga₂O₃ on Sapphire − Dependence on The Substrate Off‐Axis Angle

Thermal Conductivity of β-Phase Ga₂O₃ and (Al_xGa_1–_x)₂O₃ Heteroepitaxial Thin Films

Growth of N‐Polar Aluminum Nitride on Vicinal Sapphire Substrates and Aluminum Nitride Bulk Substrates

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Growth of N-polar GaN on vicinal sapphire substrate by metal organic chemical vapor deposition

Cited by 9 publications

References 15 publications

Towards High‐Mobility Heteroepitaxial β‐Ga2O3 on Sapphire − Dependence on The Substrate Off‐Axis Angle

Towards High‐Mobility Heteroepitaxial β‐Ga2O3 on Sapphire − Dependence on The Substrate Off‐Axis Angle

Thermal Conductivity of β-Phase Ga2O3 and (AlxGa1–x)2O3 Heteroepitaxial Thin Films

Growth of N‐Polar Aluminum Nitride on Vicinal Sapphire Substrates and Aluminum Nitride Bulk Substrates

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Towards High‐Mobility Heteroepitaxial β‐Ga₂O₃ on Sapphire − Dependence on The Substrate Off‐Axis Angle

Towards High‐Mobility Heteroepitaxial β‐Ga₂O₃ on Sapphire − Dependence on The Substrate Off‐Axis Angle

Thermal Conductivity of β-Phase Ga₂O₃ and (Al_xGa_1–_x)₂O₃ Heteroepitaxial Thin Films