Growth of GaN Single Crystals under High Nitrogen Pressures and their Characterization
TL;DR: In this article, the authors present a review of the present status of high pressure solution growth of GaN single crystals and their characterization, including the thermodynamic properties of the system, the kinetic description of the growth which include the N, dissolution, the volume transport and the surface kineties.
Abstract: The present paper reviews presentation of the present status of high pressure solution growth of GaN single crystals and their characterization. The main aspects of the growth include: the thermodynamic properties of the system, the kinetic description of the growth which include the N, dissolution, the volume transport and the surface kineties. The important properties of GaN crystals derived from optical, X-ray, electron transport and positron annihilation measurements are presented. Also etching properties and their relation to the growth morphology and doping are discussed.
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TL;DR: It is reported that applying high pressure completely prevents the decomposition and allows the stoichiometric melting of GaN and single crystals ofGaN were formed by cooling the melt slowly under high pressures and were recovered at ambient conditions.
Abstract: The synthesis of large single crystals of GaN (gallium nitride) is a matter of great importance in optoelectronic devices for blue-light-emitting diodes and lasers. Although high-quality bulk single crystals of GaN suitable for substrates are desired, the standard method of cooling its stoichiometric melt has been unsuccessful for GaN because it decomposes into Ga and N2 at high temperatures before its melting point. Here we report that applying high pressure completely prevents the decomposition and allows the stoichiometric melting of GaN. At pressures above 6.0 GPa, congruent melting of GaN occurred at about 2,220 °C, and decreasing the temperature allowed the GaN melt to crystallize to the original structure, which was confirmed by in situ X-ray diffraction. Single crystals of GaN were formed by cooling the melt slowly under high pressures and were recovered at ambient conditions.
166 citations
Additional excerpts
...For the application of high pressure, a Polish group has conducted extensive studies with their high-pressure gas apparatus and has successfully obtained thin plates of GaN single crystal...
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TL;DR: In this article, a platelet single crystal having a size of 10mm in the longest direction and 0.1mm thick was obtained in a pyrolytic BN crucible using Na purified by distillation of the 99.95% Na.
91 citations
TL;DR: In this paper, a straightforward, nonaqueous, solvothermal method for the production of nanoscale gallium nitride structures is presented. But the method is not suitable for the fabrication of nanorods.
Abstract: We report a straightforward, nonaqueous, solvothermal method for the production of nanoscale gallium nitride structures. Nanoparticles with spherical and rodlike morphologies are produced via in situ gallium azide precursor synthesis and decomposition in superheated toluene or THF. The solution reaction between gallium chloride and sodium azide produces an insoluble azide precursor that solvothermally decomposes to GaN at temperatures below 260 °C. The resulting products are poorly crystalline but thermally stable and crystallize to hexagonal GaN upon annealing at 750 °C. Product morphologies include nanoparticles (ca. 50 nm) and nanorods (ca. 300 nm lengths). Upon annealing, the nanoparticles coalesce into larger organized crystalline structures with hexagonal facets.
80 citations
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01 Jan 2016
TL;DR: In this article, the authors present a vast collection of articles on various aspects of light and its applications in the contemporary world at a popular or semi-popular level, where the world experts have come together to present the developments in this most important field of science in an almost pedagogical manner.
Abstract: Light and light based technologies have played an important role in transforming our lives via scientific contributions spanned over thousands of years. In this book we present a vast collection of articles on various aspects of light and its applications in the contemporary world at a popular or semi-popular level. These articles are written by the world authorities in their respective fields. This is therefore a rare volume where the world experts have come together to present the developments in this most important field of science in an almost pedagogical manner. This volume covers five aspects related to light. The first presents two articles, one on the history of the nature of light, and the other on the scientific achievements of Ibn-Haitham (Alhazen), who is broadly considered the father of modern optics. These are then followed by an article on ultrafast phenomena and the invisible world. The third part includes papers on specific sources of light, the discoveries of which have revolutionized optical technologies in our lifetime. They discuss the nature and the characteristics of lasers, Solid-state lighting based on the Light Emitting Diode (LED) technology, and finally modern electron optics and its relationship to the Muslim golden age in science. The book’s fourth part discusses various applications of optics and light in today's world, including biophotonics, art, optical communication, nanotechnology, the eye as an optical instrument, remote sensing, and optics in medicine. In turn, the last part focuses on quantum optics, a modern field that grew out of the interaction of light and matter. Topics addressed include atom optics, slow, stored and stationary light, optical tests of the foundation of physics, quantum mechanical properties of light fields carrying orbital angular momentum, quantum communication, and Wave-Particle dualism in action.
44 citations
TL;DR: In this article, conditions for seeded growth of GaN crystals by the Na flux method were investigated, and the maximum growth rate in the c direction was about 4 μm/h at 850 °C and 2 MPa of N2.
42 citations
References
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TL;DR: In this article, the InGaN multi-quantum-well (MQW) structure was used for laser diodes, which produced 215mW at a forward current of 2.3
Abstract: InGaN multi-quantum-well (MQW) structure laser diodes (LDs) fabricated from III-V nitride materials were grown by metalorganic chemical vapor deposition on sapphire substrates. The mirror facet for a laser cavity was formed by etching of III-V nitride films without cleaving. As an active layer, the InGaN MQW structure was used. The InGaN MQW LDs produced 215 mW at a forward current of 2.3 A, with a sharp peak of light output at 417 nm that had a full width at half-maximum of 1.6 nm under the pulsed current injection at room temperature. The laser threshold current density was 4 kA/cm2. The emission wavelength is the shortest one ever generated by a semiconductor laser diode.
2,100 citations
TL;DR: In this paper, high-brightness blue, green and yellow light-emitting diodes (LEDs) with quantum well structures based on III-V nitrides were grown by metalorganic chemical vapor deposition on sapphire substrates.
Abstract: High-brightness blue, green and yellow light-emitting diodes (LEDs) with quantum well structures based on III-V nitrides were grown by metalorganic chemical vapor deposition on sapphire substrates. The typical green LEDs had a peak wavelength of 525 nm and full width at half-maximum (FWHM) of 45 nm. The output power, the external quantum efficiency and the luminous intensity of green LEDs at a forward current of 20 mA were 1 mW, 2.1% and 4 cd, respectively. The luminous intensity of green LEDs (4 cd) was about 40 times higher than that of conventional green GaP LEDs (0.1 cd). Typical yellow LEDs had a peak wavelength of 590 nm and FWHM of 90 nm. The output power of yellow LEDs was 0.5 mW at 20 mA. When the emission wavelength of III-V nitride LEDs with quantum well structures increased from the region of blue to yellow, the output power decreased dramatically.
1,343 citations
TL;DR: Vapor deposited GaN single crystals tested for electrical and optical properties, determining band gap energy, electron concentration, etc as mentioned in this paper, were tested for testing the properties of single crystals.
Abstract: Vapor deposited GaN single crystals tested for electrical and optical properties, determining band gap energy, electron concentration, etc
1,211 citations
TL;DR: In this article, the first successful P-GaN/n-InGaN+GaN double-heterostructure (DH) blue-light-emitting diodes (LEDs) were fabricated successfully for the first time.
Abstract: P-GaN/n-InGaN/n-GaN double-heterostructure (DH) blue-light-emitting diodes (LEDs) were fabricated successfully for the first time. The output power was 125 µW and the external quantum efficiency was as high as 0.22% at a forward current of 20 mA at room temperature. The peak wavelength and the full width at half-maximum (FWHM) of the electroluminescence (EL) were 440 nm and 180 meV, respectively. This value FWHM of was the smallest ever reported for blue GaN LEDs.
564 citations
TL;DR: In this article, the influence of impurities on the growth rate of a growing crystal has been investigated and some experiments have been carried out on a set of elementary steps and a parallel sequence of steps.
Abstract: I. Crystal Surfaces in Equilibrium with the Surrounding Medium 117 The Surface Energy of Crystals 117 1. Kinks in Elementary Steps 117 2. Crystal Surface Energy. Herring's Formula 118 3. Corner Points in the Profiles of Crystal Surfaces 119 4. Surface Stability Conditions 120 5. The Equilibrium Shape of an Open Curve 121 II. Crystal Growth from Vapor 122 6. Particles Adsorbed on a Surface 123 7. The Motion of an Isolated Step 123 8. Parallel Sequences of Elementary Steps 124 9. The Normal Rate of Spiral Growth 124 10. The Motion of Macroscopic Steps 126 11. Some Experimental Results 128 12. Evaporation 129 III. Crystal Growth from the Solution and from the Melt 129 13. Introduction 129 14. The Motion of a Parallel Sequence of Elementary Steps 130 15. The Normal Growth Rate 131 16. Some Experimental Results 131 17. Growth from the Melt 132 18. The Diffusion Field and Rate of Advance of a Macroscopic Step 133 IV. The Interaction of Growing Crystals with Impurities 134 19. The Influence of Impurities on the Growth Rate 134 a) Strongly Adsorbed Impurities Captured by a Growing Crystal 135 b). Impurity Poisoning of Sinks 135 20. Nonequilibrium Capture of Impurities in Crystal Growth 137 21. Dislocation Production in Impurity Capture 139 V. Etching 139 VI. Collective Effects in the Movement of Steps 140 22. Shock Waves of Step Density 141 23. A Kinetic Equation for Steps 143 References 145
382 citations