Structure and Electronic Properties of Strained Si/Ge Semiconductor Superlattices

  • S. Ciraci
  • Inder P. Batra
Part of the NATO ASI Series book series (NSSB, volume 183)


The stability, growth, structural phase transitions, and the electronic properties of strained SiGe alloy and superlattices have been investigated by using self-consistent field pseudopotential method. The equilibrium structures of Sin/Gen (n ≤ 6) superlattices pseudomorphically restricted to the Si(001) surface are determined, and their formation enthalpies are calculated. A simple model for the formation enthalpy of superlattices is developed, whereby the activation barrier of the misfit dislocation is estimated. It is found that during the layer-by-layer growth, the energy of the topmost layer is lowered through the dimerization of atoms. The energy gap of all Sin/Gen superlattices is found to be indirect. More significantly, the energy separation between the direct and indirect gap continues to decrease with increasing n, and is only 0.07 eV for n = 6. Extended conduction band states below the confined states point to a new feature of the band offset and quantum size effect. Localized states lying deep in the valence and conduction band continua are another novel result found in this study.


Formation Energy Misfit Dislocation Formation Enthalpy Conduction Band Minimum Planar Compressive Strain 
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Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • S. Ciraci
    • 1
  • Inder P. Batra
    • 2
  1. 1.Department of PhysicsBilkent UniversityAnkaraTurkey
  2. 2.IBM Research DivisionAlmaden Research CenterSan JoseUSA

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