Domain Structures of As-Adsorbed Si(100) Surface and GaAs Overlayer

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Abstract
The surface domain structures of As-adsorbed Si(100) substrates and of subsequently overgrown GaAs films are observed by reflection high energy electron diffraction. Single-domain Si(100)2×1 is obtained by using samples cut at 4° from the (100) crystal axis towards (011). Even at a low substrate temperature of 200°C, As adsorption causes the RHEED pattern to rotate from 2×1 to 1×2, indicating formation of As-As dimers on the Si(100). This surface reconstruction does not change after thermal annealing at 650°C. Furthermore, GaAs layers are grown on two types of As-adsorbed Si(100) substrates. One is subjected to the subsequent 650°C annealing and the other has no subsequent annealing. Upon two-step growth of GaAs layers at 400°C and 630°C on these As-adsorbed Si substrates, both final GaAs surfaces reveal the 4×2 reconstruction, independent of the subsequent annealing of As-adsorbed Si substrates. Previous observation that the domain structure of GaAs on As-adsorbed Si depends on the As-adsorption temperature, is assigned to the presence of the double-domain structure of the Si(100) surface.