| Budget Amount *help |
¥7,800,000 (Direct Cost: ¥7,800,000)
Fiscal Year 1997: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1996: ¥5,300,000 (Direct Cost: ¥5,300,000)
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| Research Abstract |
Recently, growth mode of the (111) surface of group-IV semiconductors has generated great interest. However, little work has been reported on the growth fashion on the {111} polar surfaces of III-V compound semiconductors. The purpose of this work is (i) to determine the surface normal components of atomic coordinated of InSb {111} A,B- (2*2) and (ii) to study dynamical growth processes of alpha-Sn films on these surfaces by using reflection high-energy electron diffraction (RHEED). Main results are given as follows :
(i) By the quantitative analysis of RHEED rocking curves based on the dynamical diffraction theory, we have determined the surface normal atomic coordinates of the InSb {111} A,B- (2*2) surfaces which have the In-vacancy bucking structure and the Sb-trimer structure, respectively. The surface In atoms of InSb (111) A- (2*2) exhibit a large inward relaxation (-0.8). The analysis of InSb (111) B- (2*2), on the other hand, has revealed that the Sb-trimer is located at a height of -2.8 above the substrate Sb atoms, and that the prominent relaxation occurs in the subsurface region beneath the Sb-trimer.
(ii) Surfaces of Sn growing on InSb {111} A,B has been studied with use of the RHEED intensity oscillation technique. The surfaces proceed in the formation of a bilayred lattice in the whole range of film thickness. However, the geometry of the outermost surface layr is quite different in both systems : The growing surface on the InSb (111) A smoothens with the same period as the lattice formation, whereas on InSb (111) B,below and above 6 ML of Sn, smooth surfaces emerge every period of monolayr and bilayr, respectively. The monolayr-period change in surface geometry is attributed to Sb segregation on the growing surface.
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