Determination of twist angle of in-plane mosaic spread of GaN films by high-resolution X-ray diffraction

Zheng, Xiaohong; Chen, H.; Yan, Zixiang; Han, Yanjun; Yu, Huimei; Li, D.S.; Huang, Qi; Zhou, Jian

doi:10.1016/s0022-0248(03)01211-9

Cited by 94 publications

(73 citation statements)

References 11 publications

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“…The parameters of the vertical and lateral coherence length and tilt angle can be obtained from the WilliamsonHall measurement, and the twist angle from an approach, which was developed by Srikant et al [23] or from direct measurement [24], which explains the superposed effect of the tilt and twist on the broadening of the full-widths at half-maximum (FWHMs) of the off-axis plane rocking curves [25].…”

Section: Resultsmentioning

confidence: 99%

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The influence of nitridation time on the structural properties of GaN grown on Si (111) substrate

et al. 2008

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In the present paper, the effect of in-situ substrate nitridation time on crystalline quality of GaN films grown on Si (111) substrates by metal organic chemical vapor deposition (MOCVD) were investigated. A thin buffer layer of silicon nitride (SiN x ) with various thicknesses was achieved through the nitridation of substrate at different nitiridation times ranging from 0 to 660 s. The structural characteristics, such as dislocation densities, correlation lengths of columnar crystallites, the tilt and twist of the mosaic structure, and the angles of rotational disorder, were all studied in detail by using a planar and cross-sectional view of high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (HRXRD) performed at different scattering geometries. It was found that the dislocation densities, lateral coherence lengths, vertical coherence lengths, and the tilt and

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Section: Resultsmentioning

confidence: 99%

“…However, all of these methods include a complicated calculation and fitting procedure for the extraction of the twist angle from the experimental data. On the other hand, Zheng et al [24] proposed a simple empirical approach to obtain the mean twist angle directly without falling into complications.…”

Section: Resultsmentioning

confidence: 99%

The influence of nitridation time on the structural properties of GaN grown on Si (111) substrate

et al. 2008

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“…As reported in Ref. [18], the screw and edge TD densities are estimated by the formula: angles of lattice planes [19,20]. According to Eq.…”

Section: Resultsmentioning

confidence: 99%

Effect of growth temperature of initial AlN buffer on the structural and optical properties of Al-rich AlGaN

Peng

Guo

Zhang

et al. 2007

Journal of Crystal Growth

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“…The ω-scan curve broadening of the asymmetric reflection (30-32) of GaN is caused by a combination of twist and tilt; however, previous research shows that 1.14 times the FWHM of (30-32) ω-scan curve is a good approximation of the twist angle [25,26] . The XRD measurement data and the calculation results of grain sizes and dislocation densities for five GaN samples with different V/III ratio are listed in Table 1.…”

Section: Resultsmentioning

confidence: 89%

Role of lateral growth on the structural properties of high temperature GaN layer

Zhang

2008

Sci. China Ser. E-Technol. Sci.

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The role of lateral growth on the structural properties of high temperature (HT) GaN epitaxial layer has been investigated by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). Variations of the lateral growth rate of HT GaN in metal-organic chemical vapor deposition (MOCVD)can be obtained by changing the V/III ratio. It is found that under higher lateral growth rate, dislocation is easier to bend into subgrains away from c axis, and the position where bend occurs is closer to the buffer layer, however, dislocation density does not show to monotonically vary with increasing lateral growth rate. A model concerning the GaN growth dynamics and dislocation bending mechanics has been proposed to explain the correlation between lateral growth and the structural properties of GaN. GaN, lateral growth, dislocation, V/IIIDue to the high interfacial energy associated with GaN thin films on sapphire substrates, a two-step MOCVD growth process has been developed to produce a high-quality GaN films with a smooth surface [1,2] . This process involves the growth of GaN or AlN nucleation layers at low temperatures (LT) on the nitridated sapphire surface, followed by the growth of the device quality GaN film at high temperature. The buffer layer is thought to have an amorphous like structure at its deposition temperature. Before the growth of HT GaN, buffer is annealed at high temperature, crystallizes by solid phase epitaxy, and forms columnar fine crystals. GaN layer growth begins with the nucleation of islands on top of the fine crystals in the buffer. The size and density of these islands depend on the growth conditions of buffer layer [3][4][5] . During further growth, the GaN nucleation islands become bigger at both lateral and vertical directions as the result of geometric selection, then gradually coalesce and form well-developed columnar subgrain structure. Cross-sectional TEM has revealed that these islands are free of threading dislocation (TD) prior to coalescence [6,7] . However, since these islands often have small misorientations with respect to their neighbors, TD array are created during island-island coalescence to accommodate the slight misorientations between grains [3,6] . Previous works have demonstrated that control of the buffer layer growth conditions, such as growth time and annealing temperature, is essential for the film quality, since the buffer layer morphology determines the HT GaN nucleation island morphology. However, GaN microstructure characteristic could not be solely determined by the buffer layer. This indicates that besides the size and density of the initial nucleation islands, the role of the lateral growth of HT GaN cannot be ignored.It is well known that in the lateral epitaxial overgrowth (LEO) of GaN technique, TD will grow vertically to the top of the mask and bend laterally into regions parallel to the mask [8][9][10] . By contrast, synthesis of GaN nanorods, which are expected to greatly improve the photoelectronic device characteristics, requires precisely...

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Determination of twist angle of in-plane mosaic spread of GaN films by high-resolution X-ray diffraction

Cited by 94 publications

References 11 publications

The influence of nitridation time on the structural properties of GaN grown on Si (111) substrate

The influence of nitridation time on the structural properties of GaN grown on Si (111) substrate

Effect of growth temperature of initial AlN buffer on the structural and optical properties of Al-rich AlGaN

Role of lateral growth on the structural properties of high temperature GaN layer

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