High-resolution synchrotron-radiation core-level spectroscopy of decapped GaAs(100) surfaces

Abstract

We report a high-resolution core-level spectroscopy study of the (4X2)-c(8x2) GaAs (100) surface prepared by thermal decapping of surfaces grown by molecular-beam epitaxy. Ga and As 3d core levels are analyzed using very strict parameter conditions, and compared with core levels taken from cleaved GaAs(110). Two surface components are resolved in the Ga spectra while only one surface component is necessary for As. We tentatively assign the two Ga surface components to inequivalent Ga dimers in the unit cell; the As surface component is assigned to the threefold-coordinated second-layer As next to the missing row of Ga dimers. The position of the Fermi level on decapped n-type and p-type substrates is investigated in detail. The characterization of these clean decapped (100) surfaces provides a firm basis for further studies of electrical and chemical properties of metal-semiconductor interfaces.

Species intermixing and phase transitions on the reconstructed (001) surfaces of GaAs and InAs

“…Note that gallium cannot be incorporated into a single-layered c͑4ϫ4͒ structure unless g 2 is exactly 3 4 , under the assumption that the new c͑4ϫ4͒ phase exists one atomic layer below the original 2ϫ4. This high value would be inconsistent with PES and TPD data, [5][6][7]11 which show that As-As bonding is dominant in the upper layers. In fact, PES indicates a shifted Ga 3d component for the c͑4ϫ4͒ structure consistent with Ga atoms accepting more charge than in the bulk, which would be the case for second-layer substitutional Ga in the c͑4ϫ4͒ structure.…”

“…[1][2][3] Scanning tunneling microscopy ͑STM͒ has played a vital role in achieving this understanding, but several other techniques such as isotoperesolved medium energy ion scattering 4 ͑MEIS͒ and photoelectron spectroscopy [5][6][7] ͑PES͒ have also provided valuable insights particularly relating to surface composition. Some controversy remains, however, concerning the intermixing of Ga and As in the individual layers of the 2ϫ4 and c͑4ϫ4͒ surfaces.…”

Structural investigation of the three-layer system MgO/Fe/GaAs(001) by means of photoelectron spectroscopy and diffraction

“…The surface state presented by component A1 is essential for obtaining an excellent result within the fitting procedure. 39 For the Ga 3d signal, the components G1 and G2 are increasing with respect to the bulk signal B Ga at a polar angle of 60 • while the bulk signal decreases. The increase for the component G1 is larger than for the component G2, as can be seen in Fig.…”

Influence of sulfur interlayers on the Mg/GaAs(100) interface formation

“…These values ͑Table I͒ were first derived from the clean surface and thereafter optimized to provide the best fit for the complete series. 15,18 In Fig. The asymmetry parameters of the Doniach-Sunjic line shape of metallic components were achieved from fitting the core level spectra in which the metallic component is most prominent.…”

“…In the following the discussion of the chemistry will be related to p-type GaAs͑100͒ samples since n-type samples reveal very similar behavior. 15 The S treatment of the GaAs͑100͒ surface changes the As 3d and Ga 3d core level spectra dramatically. The deconvolution of this spectrum as shown in Fig.…”