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| 2. |
- Darakchieva, Vanya, 1971-, et al.
(författare)
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Optical phonons in a-plane GaN under anisotropic strain
- 2008. - 1
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Ingår i: Group-III nitrides with nonpolar surfaces: growth, properties and devices. - : Wiley. - 9783527407682 ; , s. 219-253
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This is the first monograph to discuss in detail the current stage of development of nonpolar nitrides, with specific emphasis on the three main topics of crystal growth, properties and device studies. World–class researchers summarize their own recent achievements in their respective fields of expertise, covering both nonpolar and semipolar nitride materials. The bulk of the discussion in each chapter is related to the physical properties of the material obtained by the respective technique, in particular, defect density and properties of the defects in nonpolar nitrides. In addiiton, the optical and vibrational properties are also addressed in several chapters, as is progress in heterostructures, quantum wells and dots based on the AlGaN/GaN and the InGaN/GaN systems. Finally, an outlook of the application areas of the differently grown materials is presented in most chapters, together with the capabilities and limitations of the respective growth approaches used.
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| 4. |
- Paskov, Plamen, 1959-, et al.
(författare)
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Photoluminescence study of near-surface GaN/AlN superlattices
- 2008
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. ; , s. 68940G1-
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Konferensbidrag (refereegranskat)abstract
- We report on the emission properties of GaN/AlN superlattices (SLs) grown by metalorganic chemical vapor deposition on a thick GaN layer. Nominally undoped and Si-doped SL structures with the well/barrier thickness ratio 3:1 and different SL periods are investigated. It is found that in these SLs without capping layer the energy position, intensity and linewidth of the emission are determined by the interplay of the built-in polarization field, the depletion field arising from the pinning of the Fermi level at the surface, and the screening of the electric field in the quantum well due to the both the polarization-induced two-dimension electron gas (2DEG) and the photo-generated carriers. A non-uniform equilibrium electron distribution and an electron accumulation at the bottom AlN/GaN interface are evidenced by the observed recombination of the 2DEG with the photo-excited holes occurring below the GaN bandgap.
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| 5. |
- Paskova, Tanja, 1961-, et al.
(författare)
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Defect and emission distributions in bulk GaN grown in polar and nonpolar directions : a comparative analysis
- 2008
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. ; , s. 68940D1-
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Konferensbidrag (refereegranskat)abstract
- We have investigated bulk GaN material grown by HVPE either in the conventional polar [0001] direction and subsequently sliced with nonpolar surfaces or grown in the nonpolar [11-20] direction. Spatially resolved techniques such as cathodoluminescence imaging and transmission electron microscopy, as well as profile measuring techniques such as positron annihilation spectroscopy and secondary ion mass spectroscopy were employed to directly visualize the extended structural defects, and point defect (impurity and vacancy) distributions along the growth axes. A comparative analysis of the results shows a distinctive difference in the distribution of all kind of defects along the growth axes. A significant decrease in the defect density in material grown along the polar direction, in contrast to the constant behavior of the high defect density in material grown along the nonpolar direction points out the low-defect superior quality of the former material and indicates the preferable way of producing high-quality GaN substrates with nonpolar surfaces.
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