THE ROLE OF STRAIN AND SURFACE STOCHIOMETRY IN THE SYNTHESIS OF InAs/GaAs (100) MULTILAYER COMPOUNDS

Abstract
Lattice-mismatched or strained-layer epitaxy is a particularly intriguing problem because of the promise of new materials systems and novel electronic properties derived from straininduced modification of local structure. In addition to the interest in strained-layer systems related to the development of new electronic and optoelectronic devices, the study of the dynamics of their growth using MBE promises to strongly enhance our understanding of IIIV MBE growth mechanisms. Using our RHEED controlled growth techniques, we find that in the InAs/GaAs system these materials grow in registration to the substrate, giving rise to a tetragonal distortion of the local coordination. This modification of the bonding and symmetry of the growing film has serious ramifications for the physisorbed and chemisorbed species which establish the growth front and the surface stochiometrym. The surface transport of In or Ga, the chemical incorporation of As₂ or As₄ and the details of the terrace and step distributions all show a sensitivity to bond strain and lattice mismatch. The interfacial roughness of heterojunction boundaries in these superlattice systems is likewise affected by local strain and potential variations.