Enhanced growth rate for ammonothermal gallium nitride crystal growth using ammonium iodide mineralizer

Tomida, Daisuke; Kagamitani, Yuji; Bao, Quanxi; Hazu, K.; Sawayama, H.; Chichibu, S. F.; Yokoyama, Chiaki; Fukuda, Tsuguo; Ishiguro, Tohru

doi:10.1016/j.jcrysgro.2012.04.042

Cited by 36 publications

(35 citation statements)

References 25 publications

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“…[9][10][11][12][13][14] The ammonothermal method has produced very high quality, low TDD (<10 4 cm À2 ) GaN wafers; however, poor growth rates (<4 lm/h) and purity issues limited the commercial availability of ammonothermal substrates. Imanishi et al have demonstrated GaN crystals with TDD $10 3 cm À2 via Na-flux growth; 15 however, challenges with the Na-flux method are primarily the feasibility for upscaling and cost.…”

Section: Introductionmentioning

confidence: 99%

Curvature and bow of bulk GaN substrates

Foronda

Романов

Young

et al. 2016

Journal of Applied Physics

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We investigate the bow of free standing (0001) oriented hydride vapor phase epitaxy grown GaN substrates and demonstrate that their curvature is consistent with a compressive to tensile stress gradient (bottom to top) present in the substrates. The origin of the stress gradient and the curvature is attributed to the correlated inclination of edge threading dislocation (TD) lines away from the [0001] direction. A model is proposed and a relation is derived for bulk GaN substrate curvature dependence on the inclination angle and the density of TDs. The model is used to analyze the curvature for commercially available GaN substrates as determined by high resolution x-ray diffraction. The results show a close correlation between the experimentally determined parameters and those predicted from theoretical model.

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Section: Introductionmentioning

confidence: 99%

Curvature and bow of bulk GaN substrates

Foronda

Романов

Young

et al. 2016

Journal of Applied Physics

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“…1 The ammonothermal growth is considered an efficient and scalable bulk GaN growth method, and high quality ammonothermal crystals have been achieved by several groups. [2][3][4][5] To sustain the continuous improvement of bulk GaN crystal quality, it is imperative to characterize the defect structure. However, due to the low defect density (as low as 5 Â 10 3 cm À2 ) in state of the art crystals, 6 defect characterization with conventional methods suitable for higher dislocation density materials is becoming increasingly difficult.…”

Section: Introductionmentioning

confidence: 99%

Synchrotron radiation x-ray topography and defect selective etching analysis of threading dislocations in GaN

Sintonen

Rudziński

Suihkonen

et al. 2014

Journal of Applied Physics

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The crystal quality of bulk GaN crystals is continuously improving due to advances in GaN growth techniques. Defect characterization of the GaN substrates by conventional methods is impeded by the very low dislocation density and a large scale defect analysis method is needed. White beam synchrotron radiation x-ray topography (SR-XRT) is a rapid and non-destructive technique for dislocation analysis on a large scale. In this study, the defect structure of an ammonothermal c-plane GaN substrate was recorded using SR-XRT and the image contrast caused by the dislocation induced microstrain was simulated. The simulations and experimental observations agree excellently and the SR-XRT image contrasts of mixed and screw dislocations were determined. Apart from a few exceptions, defect selective etching measurements were shown to correspond one to one with the SR-XRT results

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“…Great effort is being put into maintaining steady improvement in crystal quality of bulk GaN substrates. Ammonothermal growth of GaN is an efficient and scalable method capable of producing high quality and low dislocation density GaN crystals [1][2][3][4]. Structural characterization is critical to further improve the material quality, but characterization of defects by conventional methods is becoming increasingly difficult due to the low defect density.…”

Section: Introductionmentioning

confidence: 99%