Properties and preparation of high quality, free-standing GaN substrates and study of spontaneous separation mechanism

Ashraf, H.; Kudrawiec, R.; Weyher, J.L.; Serafińczuk, J.; Misiewicz, J.; Hageman, P.R.

doi:10.1016/j.jcrysgro.2010.05.004

Cited by 14 publications

(12 citation statements)

References 25 publications

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“…Some groups have reported that the separation took place at the GaN/sapphire interface while cooling down from the growth temperature due to build-up of high thermal stress as a result of the thermal expansion coefficients mismatch. But in some literatures, authors proposed the spontaneous separation as a consequence of the evaporation of low quality nucleation layer [17,18]. In order to further state clearly,…”

Section: A Self-separation Growth Methodsmentioning

confidence: 99%

The growth of high-quality and self-separation GaN thick-films by hydride vapor phase epitaxy

Luo

Goldsmith³

et al. 2012

Journal of Crystal Growth

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Section: A Self-separation Growth Methodsmentioning

confidence: 99%

The growth of high-quality and self-separation GaN thick-films by hydride vapor phase epitaxy

Luo

Goldsmith³

et al. 2012

Journal of Crystal Growth

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“…During cooling down of the samples after the second growth run, the GaN layers spontaneously separated from the sapphire substrate in large pieces due to high compressive strain. 26 In order to perform electrical characterization of the layers, Schottky and Ohmic contacts were made by evaporating metals on the Ga polar ͑0001͒ surface. First the Ohmic contacts were made by evaporating a 100 nm thick aluminum ͑Al͒ layer followed by the deposition of a 20 nm thick titanium ͑Ti͒ layer ͑which saves Al from oxidation͒ and annealing at 300°C for 3 min.…”

Section: Experimental Detailmentioning

confidence: 99%

Study of electric field enhanced emission rates of an electron trap in n-type GaN grown by hydride vapor phase epitaxy

Ashraf

Arshad

Faraz

et al. 2010

Journal of Applied Physics

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Electric field-enhanced emission of electrons from a deep level defect in GaN grown by hydride vapor phase epitaxy has been studied. Using the field dependent mode of conventional deep level transient spectroscopy ͑DLTS͒, several frequency scans were performed keeping applied electric field ͑12.8-31.4 MV/m͒ and sample temperature ͑300-360 K͒ constant. Arrhenius plots of the resultant data yielded an activation energy of the electron trap E ranging from E c − 0.48Ϯ 0.02 eV to E c − 0.35Ϯ 0.02 eV, respectively. The extrapolation of the as-measured field dependent data ͑activation energy͒ revealed the zero-field emission energy ͑pure thermal activation energy͒ of the trap to be 0.55Ϯ 0.02 eV. Various theoretical models were applied to justify the field-enhanced emission of the carriers from the trap. Eventually it was found that the Poole-Frenkel model associated with a square well potential of radius r = 4.8 nm was consistent with the experimental data, and, as a result, the trap is attributed to a charged impurity. Earlier, qualitative measurements like current-voltage ͑I-V͒ and capacitance-voltage ͑C-V͒ measurements were performed, and screening parameters of the device were extracted to ascertain the reliability of DLTS data.

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“…An important step in this technology is the separation of the bulk GaN layer from the substrate after the growth process. Thick GaN layers with thicknesses of several hundred microns typically separate from sapphire substrates during the cooling after the growth, but this self-separation process is accompanied by cracking of the GaN layer [1][2][3]. The cracking of a GaN layer can be suppressed by growing a bulk GaN layer with a thickness of several millimeters, or by reducing the bonding energy between a substrate and a GaN layer.…”

Section: Introductionmentioning

confidence: 99%

Free-standing 2-inch bulk GaN crystal fabrication by HVPE using a carbon buffer layer

Voronenkov

Leonidov

Bochkareva

et al. 2019

J. Phys.: Conf. Ser.

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A free-standing bulk gallium nitride layer with a thickness of 365 µm and a diameter of 50 mm was obtained by hydride vapor phase epitaxy on a sapphire substrate with a carbon buffer layer. The carbon buffer layer was deposited by thermal decomposition of methane in situ in the same process with the growth of a bulk GaN layer. The bulk GaN layer grown on the carbon buffer layer self-separated from the sapphire substrate during the cooling after the growth. The dislocation density was 8 · 10 6 cm −2 . The (0002) X-Ray rocking curve full width at half maximum was 164 arcsec. arXiv:1902.04672v2 [physics.app-ph] 17 Apr 2019 V. Voronenkov et al 2019

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Properties and preparation of high quality, free-standing GaN substrates and study of spontaneous separation mechanism

Cited by 14 publications

References 25 publications

The growth of high-quality and self-separation GaN thick-films by hydride vapor phase epitaxy

The growth of high-quality and self-separation GaN thick-films by hydride vapor phase epitaxy

Study of electric field enhanced emission rates of an electron trap in n-type GaN grown by hydride vapor phase epitaxy

Free-standing 2-inch bulk GaN crystal fabrication by HVPE using a carbon buffer layer

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