High-pressure process to produce GaN crystals

Gilbert, Donald R.; Novikov, A. F.; Patrin, Nikolay; Budai, John S.; Kelly, Frank P.; Chodelka, Robert; Abbaschian, R.; Pearton, S. J.; Singh, Rajiv K.

doi:10.1063/1.1330754

Cited by 10 publications

(3 citation statements)

References 11 publications

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“…The weak component on the higher frequency side at ∼577 cm −1 is due to sapphire, while the two component peaks on the lower frequency side at ∼558 cm −1 and ∼532 cm −1 are close to the reported values for E 1 (TO) and A 1 (TO) phonon modes, respectively [44,45]. The presence of these component peaks is indicative of the deviations from back scattering geometry [46], and the increase of their prominence in the films grown at lower N 2 percentages may be attributed to misalignment of crystallites and possible increase in disorder [47]. The variation of E 2 (high) peak position (obtained after deconvolution) with Ar and N 2 percentages is shown in figure 4(b), along with the standard value of the mode.…”

Section: Resultssupporting

confidence: 79%

Microstructural dependence of residual stress in reactively sputtered epitaxial GaN films

Monish¹,

Major²

2021

J. Phys. D: Appl. Phys.

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Epitaxial GaN films were grown on c-sapphire by rf magnetron reactive sputtering of GaAs at different partial pressures of nitrogen in Ar–N2 sputtering atmosphere. High-resolution x-ray diffraction and φ-scans reveal the mosaic growth of c-axis oriented, wurtzite GaN films. The c and a parameters were independently determined to obtain the corresponding in-plane and out-of-plane strain components. Raman measurements confirmed the in-plane strain behavior. The surface morphology and elemental composition of films were studied by atomic force microscopy and secondary ion mass spectroscopy, respectively. High-resolution ω-2θ, ω, and in-plane φ-rocking curve scans were used to obtain micro-strain, screw and edge dislocation densities, respectively. The films grown at 30%–100% N2 reveal dominance of edge (∼1012 cm−2) over screw (∼1010 cm−2) dislocations, with both approaching similar densities at lower N2 percentages. The strain data has been analyzed to separate the hydrostatic and biaxial contributions and their dependences on N2 percentage. The film grown at 100% N2 displays large hydrostatic strain and micro-strain due to the presence of excess/interstitial nitrogen. The hydrostatic strain and micro-strain decrease substantially with initial decrease of N2 percentage, but increase slightly in the films grown below 30% N2, primarily due to the incorporation of Ar. The films grown below 75% N2 display growth-related intrinsic tensile stress, originating from crystallite coalescence. The stress reversal from tensile to compressive, seen in the films grown at higher N2 percentages is primarily attributed to the incorporation of excess/interstitial nitrogen into grain boundaries and the tensile side of edge dislocations. The decrease of intrinsic tensile stress in the films grown below 30% N2 is attributed to the incorporation of Ar and their voided structure.

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Section: Resultssupporting

confidence: 79%

Microstructural dependence of residual stress in reactively sputtered epitaxial GaN films

Monish¹,

Major²

2021

J. Phys. D: Appl. Phys.

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“…In this context worth indicating is the recent discussion on GaN thermochemical and related kinetics of crystals formation and decomposition at HP-HT conditions [6,25]. Notable are also innovative HP-HT solutions in which the process is developed using a solid-phase nitrogen source to form GaN crystals in a Ga metal melt [6,26].…”

Section: Introductionmentioning

confidence: 99%

The challenge of decomposition and melting of gallium nitride under high pressure and high temperature

Porowski

Sadovyi

Gierlotka

et al. 2015

Journal of Physics and Chemistry of Solids

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“…9 Davydov et al assessed the thermochemical and pressuretemperature-composition phase diagram data for the Ga-N system. 4 Although a few reports have suggested that the melting point is greater than 2500 K, there has been no systematic study on this issue. On the other hand, an attempt to perform a high-mechanical-pressure and high-temperature process was made in order to synthesize high-quality GaN crystals in the system containing no free volume for an ambient gas.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation for evaluating melting point of wurtzite-type GaN crystal

Harafuji

Tsuchiya

Kawamura

2004

Journal of Applied Physics

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Impact response and dynamic strength of partially melted aluminum alloy J. Appl. Phys. 112, 053511 (2012) Study of strain fields caused by crystallization of boron doped amorphous silicon using scanning transmission electron microscopy convergent beam electron diffraction method J. Appl. Phys. 112, 043518 (2012) A theory for time-dependent solvation structure near solid-liquid interface J. Chem. Phys. 136, 244502 (2012) A new model of chemical bonding in ionic meltsA two-phase molecular dynamics simulation of coexisting solid and liquid has been carried out to investigate the melting point of wurtzite-type GaN crystals. The melting point is determined by examining the movement of the interface between the solid and liquid during the simulation. The potential is a two-body interatomic one composed of the long-range Coulomb interaction, the Gilbert-type short-range repulsion, the covalent bonding and covalent repulsion of the modified Morse type, and the van der Waals interaction. The melting point and the interface morphology depend on the crystallization direction. The melting point T m ͑K͒ increases with pressure P ͑GPa͒, but there appears a discontinuity in the vicinity of 8 -9 GPa. This is due to the solid-electrolyte-like behavior of Ga atoms with a partial charge in the high-pressure region. The discontinuity has not yet been confirmed by experiment. The least-squares fitted result is T m = 2538+ 177P − 4.62P 2 at pressures lower than 8 GPa and T m = 2825+ 210P −5P 2 at pressures higher than 9 GPa. The Clausius-Clapeyron relation is confirmed using calculated thermodynamic data.

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High-pressure process to produce GaN crystals

Cited by 10 publications

References 11 publications

Microstructural dependence of residual stress in reactively sputtered epitaxial GaN films

Microstructural dependence of residual stress in reactively sputtered epitaxial GaN films

The challenge of decomposition and melting of gallium nitride under high pressure and high temperature

Molecular dynamics simulation for evaluating melting point of wurtzite-type GaN crystal

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