DOI

10.1557/S1092578300000375

Date of this Version

2-9-2004

Keywords

aluminum nitride, bulk, seeded growth, sublimation, single, crystal

Abstract

AlN single crystals were grown on AlN/SiC seeds by sublimation of AlN powder in TaC crucibles in a nitrogen atmosphere. The seeds were produced by metallorganic chemical vapor deposition (MOCVD) of AlN on SiC crystals. The influence of growth temperature, growth time and source-toseed distance on the crystallinity and the crystal growth rate were investigated. Crystals were grown in an RF heated sublimation reactor at growth temperatures ranging from 1800-2000 °C, at a pressure of 600 Torr, nitrogen flow-rate of 100 sccm and source-to-seed distances of 10 and 35 mm. At 1870 °C and a source-to-seed distance of 35 mm, isolated crystals were observed with few instances of coalescence. At 1930 °C, a source-to-seed distance of 10 mm and longer growth times (~30 hrs), crystal coalescence was achieved. Above 1930 °C, the decomposition of SiC was evidently affecting the growth morphology and resulted in growth of polycrystalline AlN. After an initial nucleation period, the observed growth rates (10-30 μm/hr) were in close agreement with predictions of a growth model that assumed gas-phase diffusion controlled growth. Optical and electron microscope observations revealed step-flow growth, while X-ray diffraction results showed the single crystal nature of the grown material. Single crystalline AlN was grown over surface areas of 200-300 mm2 and was transparent and essentially colorless.

Comments

This is the published PDF of Noveski, V., Schlesser, R., Mahajan, S., Beaudoin, S., & Sitar, Z. (2004). Growth of AlN crystals on AlN/SiC seeds by AlN powder sublimation in nitrogen atmosphere. MRS Internet Journal of Nitride Semiconductor Research, 9, E2. Copyright: Cambridge University Press, Materials Research Society, it is available at their site at DOI:10.1557/S1092578300000375

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