Beta-gallium oxide(β-Ga_(2)O_(3))thin films were deposited on c-plane(0001)sapphire substrates with different mis-cut angles along<>by metal-organic chemical vapor deposition(MOCVD).The structural properties an...Beta-gallium oxide(β-Ga_(2)O_(3))thin films were deposited on c-plane(0001)sapphire substrates with different mis-cut angles along<>by metal-organic chemical vapor deposition(MOCVD).The structural properties and surface morphology of as-grownβ-Ga_(2)O_(3)thin films were investigated in detail.It was found that by using thin buffer layer and mis-cut substrate technology,the full width at half maximum(FWHM)of the()diffraction peak of theβ-Ga_(2)O_(3)film is decreased from 2°on c-plane(0001)Al_(2)O_(3)substrate to 0.64°on an 8°off-angled c-plane(0001)Al_(2)O_(3)substrate.The surface root-mean-square(RMS)roughness can also be improved greatly and the value is 1.27 nm for 8°off-angled c-plane(0001)Al_(2)O_(3)substrate.Room temper-ature photoluminescence(PL)was observed,which was attributed to the self-trapped excitons formed by oxygen and gallium vacancies in the film.The ultraviolet-blue PL intensity related with oxygen and gallium vacancies is decreased with the increas-ing mis-cut angle,which is in agreement with the improved crystal quality measured by high resolution X-ray diffraction(HR-XRD).The present results provide a route for growing high qualityβ-Ga_(2)O_(3)film on Al_(2)O_(3)substrate.展开更多
Hydrothermal(HT)ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals.In this work,ZnO bulk crystals were grown using the relatively low-cost GaN/AlOsubstrates as seeds by chemical vapor trans...Hydrothermal(HT)ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals.In this work,ZnO bulk crystals were grown using the relatively low-cost GaN/AlOsubstrates as seeds by chemical vapor transport(CVT).With the increase of growth time,the dislocation densities in the crystal decreased from about 1×10^(6) to 6×10^(3) cm^(-2).The carrier concentration decreased from 1.24×10^(19) to 1.57×10^(17)cm^(-3),while the carrier mobility increased from 63.8 to 179 cm^(2)/(V·s).The optical transmittance in the VIS-NIR wavelength increased significantly in combination with the decreasing dislocation densities and impurity concentrations.The dislocation lines and related fast diffusion paths gradually decreased and disappeared in the late growth stage,and the crystal qualities were consequently improved.The experimental results show that the properties of as-grown ZnO crystals are comparable with bulk ZnO grown on the HT substrates to some extent.The GaN/Al_(2)O_(3) seeds may have a potential application value in the industrial production of ZnO single crystals.展开更多
基金the National Key Research and Development Program of China(Grant No.2018YFB2200500)the National Natural Science Foundation(Grant Nos.62050073,62090054,61975196).
文摘Beta-gallium oxide(β-Ga_(2)O_(3))thin films were deposited on c-plane(0001)sapphire substrates with different mis-cut angles along<>by metal-organic chemical vapor deposition(MOCVD).The structural properties and surface morphology of as-grownβ-Ga_(2)O_(3)thin films were investigated in detail.It was found that by using thin buffer layer and mis-cut substrate technology,the full width at half maximum(FWHM)of the()diffraction peak of theβ-Ga_(2)O_(3)film is decreased from 2°on c-plane(0001)Al_(2)O_(3)substrate to 0.64°on an 8°off-angled c-plane(0001)Al_(2)O_(3)substrate.The surface root-mean-square(RMS)roughness can also be improved greatly and the value is 1.27 nm for 8°off-angled c-plane(0001)Al_(2)O_(3)substrate.Room temper-ature photoluminescence(PL)was observed,which was attributed to the self-trapped excitons formed by oxygen and gallium vacancies in the film.The ultraviolet-blue PL intensity related with oxygen and gallium vacancies is decreased with the increas-ing mis-cut angle,which is in agreement with the improved crystal quality measured by high resolution X-ray diffraction(HR-XRD).The present results provide a route for growing high qualityβ-Ga_(2)O_(3)film on Al_(2)O_(3)substrate.
基金Funded by the National Natural Science Foundation of China(Nos.11905199,11904299,and U1930124)。
文摘Hydrothermal(HT)ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals.In this work,ZnO bulk crystals were grown using the relatively low-cost GaN/AlOsubstrates as seeds by chemical vapor transport(CVT).With the increase of growth time,the dislocation densities in the crystal decreased from about 1×10^(6) to 6×10^(3) cm^(-2).The carrier concentration decreased from 1.24×10^(19) to 1.57×10^(17)cm^(-3),while the carrier mobility increased from 63.8 to 179 cm^(2)/(V·s).The optical transmittance in the VIS-NIR wavelength increased significantly in combination with the decreasing dislocation densities and impurity concentrations.The dislocation lines and related fast diffusion paths gradually decreased and disappeared in the late growth stage,and the crystal qualities were consequently improved.The experimental results show that the properties of as-grown ZnO crystals are comparable with bulk ZnO grown on the HT substrates to some extent.The GaN/Al_(2)O_(3) seeds may have a potential application value in the industrial production of ZnO single crystals.
