| Budget Amount *help |
¥5,500,000 (Direct Cost: ¥5,500,000)
Fiscal Year 1991: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1990: ¥4,400,000 (Direct Cost: ¥4,400,000)
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| Research Abstract |
We have used transmission electorn diffraction (TED), reflection high energy electron diffraction (RHEED) and Auger electron spectroscopy (AES) to dynamically observe the heteroepitaxial growth processes in the metals/InSb system. Firstly, prior to the dynamic al process observations, surface structures of InSb(111) InSb(001) that used as a substrate were determined on the basis of the Patterson function, Fourier analysis and least-squares refinement associated with TED : On one hand, for InSb(111)A-2x2, the measured intensities agreed well with the kinematically calculated ones of the surface structure referring to the vacancy buckling model ; for InSb(111)B-2x2, a new model where Sb trimers are adsorbed at a fourfold atop site of the outermost Sb layer has been proposed. On the other hand, regarding InSb(OO1), the Patterson analysis of observed intensities showed the clear presence of dimers on the top of the outermost layer of InSb(OOl)-c4x4. The distribution of the TED intensities
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explained well a six atom cluster model rather than a four atom cluster model. Moreover, the present TED analysis suggested that several ordered arrangements simultaneously exist on one and the same surface of InSb(OOl)-c8x2 as well as c4x4.
Secondarly, we have observed growth processes of In and Au on such established InSb(111) InSb(OOI) surfaces by using ultra high vacuumin-situ TED : The results obtained are as follows :
[I]In/InSb(111)
(1) In grew in an island-state at room temperature and had a fcc structure at the very early stage of growth.
(2) In particles experienced an ordinary epitaxial growth on InSb(111)A-2x2, whereas on InSb(111)B-2x2 they rotated to, some extent of degrees, probably being caused by the existence of Sb trimers.
[II]In/InSb(001)
On InSb(001), In particles grew with situation similar to In/InSb(111)A ; (i) island growth, having a pyramidal shape and (ii) fcc structure. Otherwise, different growth features are as follows : In partilces were arranged along the dimer array in both InSb(001)c4x4 and InSb(OOl)-c8x2 surfaces. In addition, their crystal habit exhibited tent-like, different from the initial growth form of a pyramid.
[III]Au/InSb(111)A-2x2
In this system, aROO<3>xROO<3>-Au adsorption structure has been for the first time observed at the early stage of growth. From the TED analysis, the structure was determined to be of honeycomb trimer-missing first layer (HT-MFL) type.
Thirdly, we have surveyed Ag and Sn growth processes by RHEED and AES : The results are summarized as follows :
[IV]Ag/InSb(111)A-2x2
Ag films were found to grow with a Stranski-Krastanov mode on the InSb(111)A-2x2 surface. On the other hand, at the very early stage of growth the (110) plane of the film grew parallelly to InSb(111) with the orientation of Ag<111>//InSb<110>, whereas with the subsequent growth, the parallel orientation coexisted with Ag<110>//InSb<211>.
[V]Sn/InSb(111)
The stability of Sn films which grew with a layer-by-layer mode was lowered with an increase of the coverage. On InSb(111)A, the surface of the film irreversibly underwent from the 3x3 structure, via the 2x2 and subsequently the lxl, finally the melt. However, on the InSb(111)B the predominantly different growth features were observed ; the Auger signals that were indicative of a large deviation from the corresponding theoretical curves evidenced diffusion of Sb into the Sn overlayer. This diffusion behavior heavily influenced the surface phase transition of the alpha-Sn film grown on InSb(111)B-2x2. Less
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