Heteroepitaxial growth of thickα-Ga2O3film on sapphire (0001) by MIST-CVD technique

Ma, Tongchuan; Chen, Xuanhu; Ren, Fangfang; Zhu, Suhua; Gu, Shulin; Zhang, Rong; Zheng, Yi; Ye, Jiandong

doi:10.1088/1674-4926/40/1/012804

Cited by 53 publications

(43 citation statements)

References 28 publications

(43 reference statements)

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“…Thus, more attention is urgently required to improve the quality of α-Ga 2 O 3 now and in the future. Recently, highly crystalline α-Ga 2 O 3 thin films have been successfully grown at atmospheric pressure by mist-CVD on c-sapphire substrates, whose temperatures of 400–500 °C are reasonably low and the optimal growth conditions of solution concentration, growth temperature, carrier gas velocity, and film thickness have also been investigated [12,13]. However, there is still no systematical study about how the different carrier gas affects the film quality.…”

Section: Introductionmentioning

confidence: 99%

Influence of Carrier Gases on the Quality of Epitaxial Corundum-Structured α-Ga2O3 Films Grown by Mist Chemical Vapor Deposition Method

Zhang

et al. 2019

Materials

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This report systematically investigates the influence of different carrier gases (O2, N2, and air) on the growth of gallium oxide (Ga2O3) thin films on c-plane sapphire substrates by using the mist-CVD method. Although XRD and Raman measurements show that the pure corundum-structured α-Ga2O3 with single (0006) plane orientation was successfully obtained for all three different carrier gases, the crystal quality could be greatly affected by the carrier gas. When O2 is used as the carrier gas, the smallest full-width at half maximum (FWHM), the very sharp absorption cutoff edge, the perfect lattice structure, the highest growth rate, and the smooth surface can be obtained for the epitaxial α-Ga2O3 film as demonstrated by XRD, UV-VIS, TEM, AFM (Atomic Force Microscope), and SEM measurements. It is proposed that the oxygen content in carrier gas should be responsible for all of these results. XPS (X-ray photoelectron spectroscopy) analysis also confirms that more oxygen elements can be included in epitaxial film when O2 is used as the carrier gas and thus help improve the crystal quality. The proper carrier gas is essential for the high quality α-Ga2O3 growth.

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Section: Introductionmentioning

confidence: 99%

Influence of Carrier Gases on the Quality of Epitaxial Corundum-Structured α-Ga2O3 Films Grown by Mist Chemical Vapor Deposition Method

Zhang

et al. 2019

Materials

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“…1(d). Within each individual domain, the atomic steps are straight and elongated along the [11][12][13][14][15][16][17][18][19][20] and no surface depressions within the terraces are observed. Existing theories developed for dislocation mediated surface morphologies have been employed to interpret the formation of pinned steps, spiral growth hillocks, and surface depression.…”

mentioning

confidence: 99%

“…The detailed growth conditions have been described elsewhere. 17 By increasing the growth time, a series of a-Ga 2 O 3 films were achieved with their nominal thickness ranging from 80 nm to 8 lm as determined from optical reflection spectra recorded using a UV-visible spectrometer (Lambda 950, PerkinElmer). It was reported that cracks were often formed on the surface of thick a-Ga 2 O 3 films (>3 lm) without any buffer layer, which result from the accumulated thermal stress induced by the thermal expansion mismatch between a-Ga 2 O 3 and sapphire.…”

mentioning

confidence: 99%

“…4 In this work, we tried to slow the cooling rate (<50 K/h) after the growth so that the accumulated thermal strain can be relaxed gradually and crack-free thick a-Ga 2 O 3 films (up to 6.0 lm) without any buffer layer have been achieved. 17 The microstructures were characterized by high resolution X-ray diffraction (HRXRD) using a D8 system diffractometer with a high resolution of 0.0001 . The surface morphology was characterized using atomic force microscopy (AFM) operating in the tapping mode.…”

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confidence: 99%

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On the origin of dislocation generation and annihilation in α -Ga2O3 epilayers on sapphire

Chen

Kuang

et al. 2019

Applied Physics Letters

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Epitaxial film quality is critical to the success of high-performance a-Ga 2 O 3 vertical power devices. In this work, the origins of threading dislocation generation and annihilation in thick a-Ga 2 O 3 films heteroepitaxially grown on sapphire by the mist-CVD technique have been examined by means of high-resolution X-ray diffraction and transmission electron microscopies. By increasing the nominal thickness, screw dislocations exhibit an independent characteristic with a low density of about 1.8 Â 10 6 cm À2 , while edge dislocations propagating along the c-axis are dominant, which decrease down to 2.1 Â 10 9 cm À2 in density for an 8 lm-thick a-Ga 2 O 3 layer and exhibit an inverse dependence on the thickness. In the framework of the glide analytical model, parallel edge dislocations are generated at the interface due to the misfitinduced strain relaxation, while the dislocation glide and coalescence result in the annihilation and fusion behaviors. The optimal thick a-Ga 2 O 3 with low dislocation densities may provide a prospective alternative to fully realize a-Ga 2 O 3 power devices.

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“…The calculated band gaps of α‐, β‐, and κ‐Ga 2 O 3 are consistent with experiments and earlier theoretical reports. [ 14,48–50 ] The wide band gaps are particularly important for next‐generation semiconducting devices operating at much higher temperatures.…”

Section: Resultsmentioning

confidence: 99%

Discovery of New Polymorphs of Gallium Oxides with Particle Swarm Optimization‐Based Structure Searches

Wang

Faizan

et al. 2020

Adv Elect Materials

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Gallium oxide (Ga2O3) has attracted significant research interest for next‐generation high‐efficiency power devices because of its unique electronic properties such as ultra‐wide band gap, high breakdown electric field, and large Baliga’s figure of merit. Ga2O3 crystallizes in a series of reported polymorphs including β‐, α‐, ε‐, κ‐, γ‐, and δ‐Ga2O3, the structures of some of which are still in serious controversy. A polymorph structure search study of Ga2O3 is herein performed by combining particle swarm optimization with first‐principles energetic calculations. In addition to producing the predominant experimental known phases of β‐, α‐, and κ‐Ga2O3, two new polymorphs are found with space group P1true¯ and Pmc21 consisting of four‐ and five‐fold coordinated Ga. They show comparable energy with β‐ and α‐Ga2O3 with the energy difference of several meV per atom, and exhibit robust phonon stability. Similarly, the new phases show quite wide band gaps and small electron effective masses by comparing it with other known phases. The Pmc21 phase shows a calculated spontaneous polarization of 0.277 C m−2, close to that of ε/κ‐Ga2O3. The systemic structure searches also establish a structural relationship between ε‐Ga2O3 and κ‐Ga2O3 and how the electronic properties vary with polymorphic phase change.

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Heteroepitaxial growth of thickα-Ga₂O₃film on sapphire (0001) by MIST-CVD technique

Cited by 53 publications

References 28 publications

Influence of Carrier Gases on the Quality of Epitaxial Corundum-Structured α-Ga2O3 Films Grown by Mist Chemical Vapor Deposition Method

Influence of Carrier Gases on the Quality of Epitaxial Corundum-Structured α-Ga2O3 Films Grown by Mist Chemical Vapor Deposition Method

On the origin of dislocation generation and annihilation in α -Ga2O3 epilayers on sapphire

Discovery of New Polymorphs of Gallium Oxides with Particle Swarm Optimization‐Based Structure Searches

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