| 1. |
- Beshkova, Milena, et al.
(författare)
-
Low-pressure sublimation epitaxy of AlN films - growth and characterization
- 2004
-
Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 76, s. 143-146
-
Tidskriftsartikel (refereegranskat)abstract
- Epitaxial layers of aluminum nitride have been grown at temperatures 1900-2400degreesC on 10 x 10 mm(2) 4H-SiC substrate via sublimation recondensation in an RF heated graphite furnace. The source material was polycrystalline sintered AlN. A maximum growth rate of about 100 mum/h was achieved at 2400degreesC and seed to source distance of 1 mm. The surface morphology reflects the hexagonal symmetry of the seed suggesting an epitaxial growth. This was confirmed by X-ray diffraction (XRD). The spectra showed very strong and well-defined (0002) reflection position at around 36.04degrees in symmetric Theta-2Thetascans for all samples. Micro-Raman spectroscopy reveals that the films have a wurtzite structure. It is evidenced by the appearance of the A(1) (TO) (at 601 cm(-1)) and E-2((2)) (at 651 cm(-1)) lines in the spectra. Secondary-ion mass spectroscopy (SIMS) results showed a low concentration of carbon incorporation in the AlN films. A correlation between the growth conditions and properties of the AlN layers was established.
|
|
| 2. |
- Beshkova, M., et al.
(författare)
-
Properties of AlN epitaxial layers on 6H-SiC substrate grown by sublimation in argon, nitrogen, and their mixtures
- 2006
-
Ingår i: Materials Science & Engineering. - : Elsevier. - 0921-5107 .- 1873-4944. ; 129:1-3, s. 228-231
-
Tidskriftsartikel (refereegranskat)abstract
- Epitaxial layers of aluminum nitride (AlN) have been grown at temperature 1900 °C on 10 mm × 10 mm 6H-SiC substrate via sublimation-recondensation in RF heated graphite furnace. The source material was polycrystalline sintered AlN. Growth of AlN layers in pure nitrogen, mixed nitrogen/argon and pure argon atmosphere of 50 mbar were compared. A maximum growth rate of about 30 µm/h was achieved in pure nitrogen atmosphere. The surface morphology reflects the hexagonal symmetry of the seed, which is characteristic of an epitaxial growth for samples grown in a pure nitrogen and mixed nitrogen/argon atmosphere. X-ray diffraction (XRD) measurements show very strong and well defined (0 0 0 2) reflection positioned at around 36° in symmetric ?-2? scans. Micro-Raman spectroscopy reveals that the films have a wurtzite structure. Secondary-ion mass spectroscopy (SIMS) results showed a low concentration of carbon incorporation in the AlN layers. This study demonstrates that nitrogen is necessary for the successful epitaxial growth of AlN on 6H-SiC by sublimation. © 2006 Elsevier B.V. All rights reserved.
|
|
| 3. |
- Beshkova, Milena, et al.
(författare)
-
Properties of AlN layers grown by sublimation epitaxy
- 2003
-
Ingår i: Materials Science Forum, Vols. 433-436. ; , s. 995-998
-
Konferensbidrag (refereegranskat)abstract
- Epitaxial layers of aluminum nitride (AlN)less than or equal to 80 mum thick have been grown at the temperatures 1900 and 2100 degreesC on 10x10mm(2) 4H-SiC substrates via sublimation recondensation in a RF heated graphite furnace. The source material was polyerystalline sintered AlN. A maximum growth rate of 80 mum/h was achieved at 2100degreesC and seed to source separation of I mm. The surface morphology reflects the hexagonal symmetry of the seed that suggesting an epitaxial growth. All crystals show strong and well defined single crystalline XRD patterns. Only the (002) reflection positioned at around 36.04 was observed in symmetric Theta-2Theta scan. The rocking curves FWHM (full width half maximum) and peak positions arc reported.
|
|
| 4. |
- Beshkova, Milena, et al.
(författare)
-
Sublimation epitaxy of AIN layers on 4H-SiC depending on the type of crucible
- 2003
-
Ingår i: Journal of materials science. Materials in electronics. - 0957-4522 .- 1573-482X. ; 14:10-12, s. 767-768
-
Tidskriftsartikel (refereegranskat)abstract
- Epitaxial layers of aluminum nitride less than or equal to335 mum thick have been grown attemperatures of 1900 and 2100degreesC on 10 x 10 mm(2) (0001)-oriented alpha(4H) silicon carbide (SiC), with growth times of 1 and 4h, via sublimation-recondensation in a RF-heated graphite furnace. The source material was polycrystalline AIN. The sublimation process was performed in three types of graphite (C) crucible: C-1, C-2 with inner diameters of 35 and 51 mm, respectively, and C-3 with the same inner diameter as C-1, but coated with a layer of TaC. The surface morphology reflects the hexagonal symmetry of the substrate, suggesting an epitaxial growth for samples grown in C-1 and C-3 crucibles for all growth conditions. The same symmetry is observed for AIN layers grown in the C-2 crucible, but only at 2100degreesC. X-ray diffraction analyses confirm the epitaxial growth of AIN samples with the expected hexagonal symmetry. A high-resolution X-ray diffractometer was used to assess the quality of the single crystals. A full width at half maximum of 242 arcsec was achieved for an AIN layer grown in the crucible coated with TaC. (C) 2003 Kluwer Academic Publishers.
|
|
| 5. |
- Beshkova, Milena, et al.
(författare)
-
Sublimation epitaxy of AlN layers grown by different conditions on 4H-SiC substrates
- 2007
-
Ingår i: Journal of Optoelectronics and Advanced Materials. - 1454-4164 .- 1841-7132. ; 9:1, s. 213-216
-
Tidskriftsartikel (refereegranskat)abstract
- Epitaxial layers of aluminium nitride were grown at temperature 2100 degrees C on 10X10 mm(2) 4H-SiC substrates via a sublimation-recondensation method in an RF heated graphite furnace. The source material was polycrystalline sintered AIN. Growths of AIN layers in vacuum and pure nitrogen at 20 mbar were compared. MA maximum growth rate of 70 mu m/h was achieved in a pure N-2 atmosphere. The surface morphology reveals the hexagonal symmetry of the seeds, suggesting an epitaxial growth. This was confirmed by High-Resolution X-Ray Diffraction. The spectra showed a strong and well defined (0002) reflection positioned at 36.04 degrees in a symmetric theta-2 theta scan for both samples. Micro-Raman spectroscopy revealed that the films had a wurtzite structure. Rutherford Backscattering Spectrometry indicated the quality with a relative chi(min) parameter 0.68.
|
|
