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n Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie - Epitaksie - oriënteringskriterium : research and review article

Volume 20, Issue 3_4
  • ISSN : 0254-3486
  • E-ISSN: 2222-4173

Abstract

<b>Epitaxy : criterion for orientation</b> <br>This review is motivated by the impact of epitaxy - the oriented overgrowth of a thin crystalline layer (the epilayer) on a crystalline substrate - in pursuit of perfection in crystallinity as needed in high grade technology and fundamental studies. While acceptable knowledge with respect to the thermodynamic stability and growth modes of epitaxial layers is available, need exists for a reliable, simple criterion for epitaxial growth in order to facilitate the selection of suitable materials. Frank and Van der Merwe have proposed a sufficient criterion. A clear indication of a necessary and sufficient condition has emanated from a thermodynamic theoretical study of rigid model epitaxy at fcc (111) / bcc (110) interfaces. This study has identified, as important role players : (i) the matching of atomic rows across the contact interface, (ii) the crystalline interfacial source of periodic epilayer-substrate interaction, including its Fourier representation and (iii) the magnitude of the Fourier coefficients. The objectives have been finalised by (a) the calculation of optimum Fourier coefficients and (b) the reciprocal space Fourier series description of the periodic interaction, including the structure factors as evidence of the contributions from atomic planes further away from the contact plane and the analytical formulation of the desired criterion.

Hierdie oorsig is gemotiveer deur die impak van epitaksie - die georiënteerde groei van 'n kristallyne dunlagie (die epilagie) op 'n kristallyne substraat - in die nastreef van perfekte kristalliniteit soos benodig word in hoëgraadtegnologie en fundamentele studies. Terwyl aanvaarde kennis met betrekking tot die termodinamiese stabiliteit en groeiwyse van epitaksiale lagies beskikbaar is, is daar steeds 'n dringende behoefte aan 'n betroubare maar eenvoudige kriterium vir epitaksiale groei, ten einde die seleksie van geskikte materiale te vergemaklik. Frank en Van der Merwe het wel 'n voldoende kriterium voorgestel, maar duidelike aanduidings van 'n nodige en voldoende kriterium het eers voortgespruit uit 'n termodinamies-teoretiese studie gegrond op 'n starremodel van fcc (111) / bcc (110)-epitaksie.Hierdie studie het (i) die passing van atoomrye oor die kontakvlak, (ii) die kristallyne kontakvlak as oorsprong van epilagiesubstraat periodiese wisselwerking met die Fourier-voorstelling daarvan en (iii) die grootte van die Fourier-koëffisiënte uitgewys as vername rolspelers. Die doelwitte is gefinaliseer deur (a) die berekening van optimum Fourier-koëffisiënte en (b) die beskrywing van die omgekeerde tralieruimte van die periodiese wisselwerking, insluitende struktuurfaktore as aanduiding van die bydraes vanaf atoomvlakke verder weg van die kontakvlak, en die analitiese formulering van die gesogte kriterium.

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/content/aknat/20/3_4/EJC20294
2001-09-01
2019-10-20

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