Physical Review Letters · 1994 · 288 citations · 23 references
Natural SciencesMaterials EngineeringMaterials ScienceCondensed Matter PhysicsCrystal StructureSemiconductor MaterialsCrystallographyElectron DiffractionElectron MicroscopyScanning Probe MicroscopySemiconductor Crystal GrowthSemiconductor PhysicsAtomic-scale Surface ImagingElectron Diffraction TheoryReflection High-energy Electron DiffractionScanning Electron MicroscopyScanning Electron Microscopy AnalysisScanning Tunneling SpectroscopyUnit Cell GeometryVacancies
Scanning tunneling microscope (STM) images together with reflection high-energy electron diffraction (RHEED) showed for the first time convincingly that the molecular-beam epitaxially grown GaAs(001)-(2 \ifmmode\times\else\texttimes\fi{} 4) $\ensuremath{\alpha}$, $\ensuremath{\beta}$, and $\ensuremath{\gamma}$ phases all have the same outermost surface layer of the unit cell, which consists of two As dimers and two dimer vacancies. Based on the STM and RHEED observations and dynamical RHEED calculation, a structure model consistent with various observations is proposed.
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