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AlxGa1-xN bulk single crystals: Temperature dependence of Al solubility

Janusz Karpinski 1Peter Geiser 1Jan Jun 1S. M. Kazakov 1Peter Wägli 1Leonhard Klemm 2Bertram Batlogg 1

1. Laboratory for Solid State Physics ETH (ETH), Schafmatstr. 16, Zürich 8093, Switzerland
2. Isotope Geochemistry and Mineral Resources ETHZ, Zürich, Switzerland


Bulk AlxGa1-xN and GaN single crystals have been grown, using (Ga,Al) alloys and pure Ga under high nitrogen pressure. Gas (up to 15 kbar) and solid pressure medium setups (up to 35 kbar) are used to provide the pressure required for phase stabilization. The solubility of Al was studied by growing crystals at various temperatures (1400 - 1750C). Mass spectrometric analysis reveals a rapidly increasing Al solubility at higher temperature. Thus, the growth temperature, together with the composition of the starting materials, serves as a parameter to control the Al content. For the maximum temperature of the gas autoclave (T=1600C) an upper limit of ~2% Al is determined. Using the solid pressure medium setup (Tmax=1750C) AlxGa1-xN crystals with x=0.3 and a size of up to 0.6 x 0.4 x 0.2 mm3 are synthesized. X-ray diffraction investigations confirm the growth of the single crystalline AlxGa1-xN phase. Room temperature photoluminescence spectroscopy shows a blue-shift by up to ~0.4 eV of the band gap related peak, further confirming significant Al substitution.


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Presentation: poster at E-MRS Fall Meeting 2004, Symposium C, by Janusz Karpinski
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-07-29 08:13
Revised:   2009-06-08 12:55