Misoriented Epitaxial Growth of (111)CoSi 2 on Offset (111)Si Substrates

Abstract

ABSTRACTSingle crystal epitaxial films of CoSi2 were grown by MBE on various (111)Si single crystal substrates, whose surfaces were purposely tilted towards the < 110>>g, direction by small angles ϕg,†, 0°, ≤ϕg, ≤, 4° measured between the surface normal and the < 111>>g, direction of Si. The actual offset angle, .ϕ8,, was determined by back Laue reflection method. The average perpendicular strain of the CoSi2 epilayer, ε┵, and the < 111 >f orientation of the epitaxial CoSi2 film were determined by double crystal diffractometry. We find that the misorientation angle, a, measured between the Si < 111>g, and CoSi2 < 111>f directions, increases linearly with the offset angle, ϕg, up to ϕg, = 4°. A simple geometrical model is developed which predicts that α = ε┵ × tan ϕg,. The model agrees quantitatively with the experimental data. The equivalent strain energy associated with the misorientation is approximated by that of a low angle tilt boundary. The misorientation angle α of the equilibrium state, determined by minimizing the total strain energy of the epitaxial film, is nonzero in general.