Growth of GaN on Porous SiC by Molecular Beam Epitaxy

Sagar, Ashutosh; Feenstra, R. M.; Freitas, J. A.

doi:10.1002/9780470751817.ch5

Cited by 5 publications

(5 citation statements)

References 24 publications

(24 reference statements)

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“…High defect densities, cracking, and/or excessive bowing due to the lattice and/or thermal mismatch worsen the device's electrical and physical performance. Sagar et al [26] have demonstrated that a reduction in dislocation density from about 10 10 -10 12 per cm 2 in a template prepared using molecular beam epitaxy could be reduced to about 2.5 Â 10 9 per cm 2 , if a porous SiC substrate is employed, and lower values utilizing metal organic vapor phase epitaxy as well [27,28]. The lattice mismatch between GaN (0001) and the most common substrate sapphire (0001) is 13.8% with a thermal expansion coefficient mismatch of À25%.…”

Section: Lattice-mismatch Stresses In a Circular Film-substrate Assemblymentioning

confidence: 99%

Predicted Thermal- and Lattice-Mismatch Stresses

Suhir¹

2015

Handbook of Crystal Growth

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Section: Lattice-mismatch Stresses In a Circular Film-substrate Assemblymentioning

confidence: 99%

Predicted Thermal- and Lattice-Mismatch Stresses

Suhir¹

2015

Handbook of Crystal Growth

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“…Considering the formulas (32) and (33), the solutions (29) can be written as follows: In the case of sufficiently long (large l values) and/or stiff (large k values) assemblies the formulas (34) yield:…”

Section: = Klmentioning

confidence: 99%

“…Such substrate is more compliant, is able to relieve the interfacial lattice-mismatch stresses and to retard dislocation propagation into the body of the growing film. Numerous subsequent investigations, both theoretical and experimental (see, e.g., [20][21][22][23][24][25][26]), were triggered by the publications [18,19], and various epitaxial techniques were employed to grow GaN layers on suitable substrates [27][28][29][30][31][32][33]. We would like to point out, however, that we view the use a polished or otherwise flattened substrate as the most promising GaN technology that enables one to get rid altogether of lattice mismatch stresses.…”

Section: Introductionmentioning

confidence: 99%

Stress related aspects of GaN technology physics

Suhir

2015

SPIE Proceedings

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Simple, easy-to-use and physically meaningful analytical models have been developed for the assessment of the combined effect of the lattice and thermal mismatch on the induced stresses in an elongated bi-material assembly, as well as on the thermal mismatch on the thermal stresses in a tri-material assembly, in which the lattice mismatched stresses are eliminated in one way or another. This could be done, e.g., by using a polished or an etched substrate. The analysis is carried out in application to Gallium Nitride (GaN)-Silicon Carbide (SiC) and GaN-diamond (C) filmsubstrate assemblies. The calculated data are obtained, assuming that no annealing or other stress reduction means is applied. The data agree reasonably well with the reported (available) in-situ measurements. The most important conclusion from the computed data is that even if a reasonably good lattice match takes place (as, e.g., in the case of a GaN film fabricated on a SiC substrate, when the mismatch strain is only about 3%) and, in addition, the temperature change (from the fabrication/growth temperature to the operation temperature) is significant (as high as 1000 C), the thermal stresses are still considerably lower than the lattice-mismatch stresses. Although there are structural and technological means for further reduction of the lattice-mismatch stresses (e.g., by high temperature annealing or by providing one or more buffering layers, or by using patterned or porous substrates), there is still a strong incentive to eliminate completely the lattice mismatch stresses. This seems to be indeed possible, if polished or otherwise flattened (e.g., chemically etched) substrates and sputter deposited GaN film is employed. In such a case only thermal stresses remain, but even these could be reduced, if necessary, by using compliant buffering layers, including layers of variable compliance, or by introducing variable compliance into the properly engineered substrate. In any event, it is expected that strong adhesion could be achieved by using an appropriate fabrication technology, so that no GaN film cracking would be possible, if the film is in tension, or delamination buckling could occur if the film is in compression. The developed models can be used to assess the possibilities and opportunities associated with GaN materials technology.

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“…These materials include hexagonal SiC, which has been the subject of growing interest [6,7]. Moreover, there are numerous examples of the growth and fabrication of high-quality GaN and ZnO layers [8][9][10][11][12][13][14][15][16]. Importantly, sonification techniques have been demonstrated to be effective in dispersing 2D nanostructures in water [9].…”

Section: Introductionmentioning

confidence: 99%

Stimulation of Biological Structures on the Nanoscale Using Interfaces with Large Built-In Spontaneous Polarizations

Zia,

Stroscio,

Dutta

2024

Materials

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The electric potential stimulation of biological structures in aqueous environments is well-known to be a result of the gating of voltage-gated ion channels. Such voltage-gated ion channels are ubiquitous in the membranes of a wide variety of cells and they play central roles in a wide variety of sensing mechanisms and neuronal functions in biological systems. Experimental studies of ion-channel gating are frequently conducted using path-clamp techniques by placing a cumbersome external electrode in the vicinity of the extracellular side of the ion channel. Recently, it has been demonstrated that laser-induced polarization of nanoscale quantum dots can produce voltage sufficient to gate voltage-gated ion channels. This study specifically focuses on a new method of gating voltage-gated ion channels using 2D structures made of materials exhibiting large naturally occurring spontaneous polarizations, thereby eliminating the need for an external electrode or an illuminating laser. The work presents the use of self-polarizing semiconductor flakes, namely, 2H-SiC, ZnO, and GaN, to produce electric potential that is sufficient to gate voltage-gated ion channels when existing in proximity to it.

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Growth of GaN on Porous SiC by Molecular Beam Epitaxy

Cited by 5 publications

References 24 publications

Predicted Thermal- and Lattice-Mismatch Stresses

Predicted Thermal- and Lattice-Mismatch Stresses

Stress related aspects of GaN technology physics

Stimulation of Biological Structures on the Nanoscale Using Interfaces with Large Built-In Spontaneous Polarizations

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