Control of threading dislocation density at the initial growth stage of AlN on c-sapphire in plasma-assisted MBE

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• 作者：D.V. Nechaev ; P.A. Aseev ; V.N. Jmerik ; P.N. Brunkov ; Y.V. Kuznetsova ; A.A. Sitnikova ; V.V. Ratnikov ; S.V. Ivanov
• 关键词：A1. Dislocation ; A3. Molecular beam epitaxy ; A3. Migration enhanced epitaxy ; B2. Semiconducting aluminium compounds
• 刊名：Journal of Crystal Growth
• 出版年：2013
• 出版时间：1 September, 2013
• 年：2013
• 卷：378
• 期：Complete
• 页码：319-322
• 全文大小：882 K

文摘

Crystalline properties of (1-2)-¦Ìm-thick AlN buffer layers grown by plasma-assisted molecular-beam epitaxy (PA MBE) on c-Al₂O₃ substrates with different AlN nucleation layers have been studied. The best quality layers are obtained on 50-nm-thick nucleation AlN layers grown by a migration enhanced epitaxy (MEE) at substrate temperature of 780 ¡ãC. In this case the buffer layers possess the lowest FWHM values of the symmetric AlN(0002) and skew symmetric AlN(10-15) x-ray rocking curve peaks of 469 and 1025 arcsec, respectively, which correspond to the screw and edge threading dislocation densities of 4.7¡Á10⁸ cm^?2 and 5.9¡Á10⁹ cm^?2. This improvement seems to be related with the larger diameter of the flat-top grains in the AlN nucleation layers grown in the MEE mode at high substrate temperatures.