The effect of a slight mis-orientation angle of c-plane sapphire substrate on surface and crystal quality of MOCVD grown GaN thin films

2004 ◽  
Vol 1 (10) ◽  
pp. 2483-2486 ◽  
Author(s):  
Seong-Woo Kim ◽  
Hideo Aida ◽  
Toshimasa Suzuki
Keyword(s):  
Thin Films ◽  
Sapphire Substrate ◽  
Orientation Angle ◽  
Crystal Quality

Influence of Mis-Orientation of C-plane Sapphire Substrate on the Early Stages of MOCVD Growth of GaN Thin Films

2004 ◽  
Vol 831 ◽  
Author(s):  
Seong-woo Kim ◽  
Hideo Aida ◽  
Toshimasa Suzuki
Keyword(s):  
Thin Films ◽  
Sapphire Substrate ◽  
Orientation Angle ◽  
Rocking Curve ◽  
Sapphire Substrates ◽  
Early Stages ◽  
Mocvd Growth ◽  
The Difference ◽  
Afm Observation

ABSTRACTWe have studied the early stages of GaN growth to realize the growth mechanism of GaN thin films on mis-oriented sapphire substrates which affects the surface and crystal quality of GaN thin films. As the result, it was found that the larger mis-orientation angle helps the growth of the larger grain of GaN and leads to the earlier shift of growth mode from 3D to 2D. The AFM observation of closed-coalesced GaN thin films revealed the difference in the micro-step structures by the mis-orientation angle of sapphire substrate. The result of x-ray rocking curve as a function of mis-orientation angle well matched with the microstructure of GaN surface, indicating that the larger mis-orientation angle helps the column ordering of GaN crystals.

Annealing Time Dependence on 1.5μm Photoluminescence of Laser-Ablated β-FeSi2

2005 ◽  
Vol 891 ◽  
Author(s):  
Shin-ichiro Uekusa ◽  
Kunitoshi Aoki ◽  
Mohammad Zakir Hossain ◽  
Tomohiro Fukuda ◽  
Noboru Miura
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Thermal Diffusion ◽  
Annealing Time ◽  
Crystal Quality ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Time

ABSTRACTWe prepared β-FeSi2 thin-films by using a Pulsed Laser Deposition (PLD) method and succeeded to observe photoluminescence (PL) around 1.5 μm corresponding to β-FeSi2 band from the long-time and high-temperature annealed β-FeSi2 thin-films. The β-FeSi2 thin-films were ablated on Si(111) substrates heated at 550°C. After ablation, long-time and high-temperature thermal annealing was performed in order to improve the crystal-quality. Annealing times were 5, 10, 20 and 40 hrs, and annealing temperature was kept at 900 °C. Crystallinity was evaluated by an X-ray diffraction (XRD) measurement. We have observed eminent improvement on crystal-quality of β-FeSi2 thin-films. Annealed samples show (220) or (202) X-ray diffraction signals of β-FeSi2 and the full width at half maximum (FWHM) of these peaks were 0.27° although the thickness of the samples decreased with annealing time. Thermal-diffusion of Si atoms was observed from substrate to thin-films. Fe atoms in the ablated thin-films also diffused into the substrate. The relationship between the thickness of β-FeSi2 thin-films and the thermal-diffusion were investigated with rutherford backscattering (RBS) measurement. Maximum photoluminescence intensity around 1.5 μm was observed from the thickest β-FeSi2 thin-film with only 5 hrs annealing.

Effect of in situ thermal treatment during growth on crystal quality of GaN epilayer grown on sapphire substrate by MOVPE

2001 ◽  
Vol 222 (1-2) ◽  
pp. 110-117 ◽  
Author(s):  
H.Z Xu ◽  
K Takahashi ◽  
C.X Wang ◽  
Z.G Wang ◽  
Y Okada ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Sapphire Substrate ◽  
Crystal Quality

Improvement of crystal quality of AlN grown on sapphire substrate by MOCVD

2010 ◽  
Vol 45 (7) ◽  
pp. 703-706 ◽  
Author(s):  
Mu-Jen Lai ◽  
Liann-Be Chang ◽  
Tzu-Tao Yuan ◽  
Ray-Ming Lin
Keyword(s):  
Sapphire Substrate ◽  
Crystal Quality

Improvement in the crystal quality of non-polar a-plane GaN directly grown on an SiO2 stripe-patterned r-plane sapphire substrate

CrystEngComm ◽  
2019 ◽  
Vol 21 (34) ◽  
pp. 5124-5128 ◽  
Author(s):  
Shen Yan ◽  
Junhui Die ◽  
Caiwei Wang ◽  
Xiaotao Hu ◽  
Ziguang Ma ◽  
...  
Keyword(s):  
Sapphire Substrate ◽  
Crystal Quality ◽  
High Quality ◽  
Patterned Sapphire Substrate ◽  
Direct Growth

In this work, high-quality a-plane GaN was obtained by direct growth on a stripe-patterned sapphire substrate.

scholarly journals Effects of Thermal Annealing on Optical Properties of Be-Implanted GaN Thin Films by Spectroscopic Ellipsometry

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 439
Author(s):  
Wenwang Wei ◽  
Jiabin Wang ◽  
Yao Liu ◽  
Yi Peng ◽  
Mudassar Maraj ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Gallium Nitride ◽  
Thermal Annealing ◽  
Spectroscopic Ellipsometry ◽  
Communication Systems ◽  
Variable Temperature ◽  
Crystal Quality ◽  
Surface Decomposition

Wide bandgap III-V compounds are the key materials for the fabrication of short-wavelength optical devices and have important applications in optical displays, optical storage devices and optical communication systems. Herein, the variable-angle spectroscopic ellipsometry (SE) measurements are performed to investigate the thickness and optical properties of beryllium-implanted gallium nitride thin films that have been deposited on (0001) sapphire substrates by using low-pressure metalorganic chemical vapor deposition (LPMOCVD). The film layer details are described by using Parametric Semiconductor oscillators and Gaussian oscillators in the wavelength range of 200–1600 nm. The thickness, refractive indices and extinction coefficients of the Be-implanted films are determined at room temperature. Analysis of the absorption coefficient shows that the optical absorption edge of Be-implanted films changes from 3.328 eV to 3.083 eV in the temperature range of 300–850 K. With the variable temperature, Eg is demonstrated to follow the formula of Varshni. A dual-beam ultraviolet–visible spectrophotometer (UV–VIS) is used to study the crystal quality of samples, indicating that the quality of rapid thermal annealing (RTA) sample is better than that unannealed sample. By transport of ions in matter (TRIM) simulation and SE fitting the depths of Be implanted gallium nitride (GaN) films are estimated and in good agreement. The surface and cross-section morphologies are characterized by atomic force microscopy (AFM) and scanning electron microscope (SEM), respectively. The surface morphologies and thickness measurements of the samples show that RTA can improve crystal quality, while increasing the thickness of the surface roughness layer due to partial surface decomposition in the process of thermal annealing.

Crystalline anisotropy of β-Ga2O3 thin films on c-plane GaN template and sapphire substrate

2021 ◽  
Author(s):  
Xiaocui Ma ◽  
Rui Xu ◽  
Yang Mei ◽  
Leiying Ying ◽  
Hao Long ◽  
...  
Keyword(s):  
Thin Films ◽  
Sapphire Substrate ◽  
Lattice Mismatch ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystallographic Anisotropy ◽  
Crystalline Anisotropy

Abstract In this work, crystalline anisotropy of heteroepitaxial (-201) β-Ga2O3 films on c-plane sapphire substrate and GaN template was investigated by X-ray diffraction. The (-201) ω-scan broadening of β-Ga2O3 on GaN exhibited six-fold rotational symmetric anisotropy along different azimuths, with maxima along [010] and minima along [102] direction, respectively. However, in case of β-Ga2O3 on sapphire, it was nearly isotropic. Smaller lattice mismatch between β-Ga2O3 and GaN were taken into account to explain the discrepancy, which also explained the better quality of β-Ga2O3 deposited on GaN. Our results presented a new viewpoint to the crystallographic anisotropy of (-201 ) β-Ga2O3 thin films.

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