Electronic properties of GaAs surfaces as characterized by inverse photoemission and Auger photoelectron coincidence spectroscopy
The unoccupied electronic band structure of GaAs(100) has been probed using k-resolved inverse photoemission spectroscopy. The use of As-capped MBE-grown GaAs(100) surface has enabled us to obtain well-ordered surfaces that exhibit reconstructions characteristic of both the As-terminated (2 x 4) and the Ga-terminated (4 x 2) GaAs(100) surfaces. By studying the electronic structure of two different surface reconstructions on the same bulk semiconductor, we have been able to correlate the electronic structure of GaAs(100) with its geometric structure. In particular, we have detected a surface state at {approximately} 1.6 eV above the Fermi level that disperses with the incident electron angle. This state has been associated with the empty Ga-dangling bond and is only seen on the Ga-terminated (4 x 2) surface of GaAs(100). The energy of this state, is significantly higher than predicted by total energy DOS calculations. This discrepancy has been associated with quasiparticle excitations not included in the calculations. Using Auger photoelectron coincidence spectroscopy (APECS), we have also studied the core-valence-valance Auger decay process for the GaAs(110) surface. APECS enables us to independently separate the Ga-derived and As-derived Auger spectra and to clearly resolve the s-s and s-p Auger contributions. This has led to the discovery of surface-specific electron correlation effects, which have been directly observed for the first time in this study. We have also investigated the growth of a new class of metallic overlayers on III-V semiconductors: thermally stable, epitaxial, single crystal metallic compound growth on MBE-grown GaAs(100). In particular, we have grown CoGa and ErAs metallic thin films on GaAs(100) and have investigated their properties using a variety of techniques to study the quality of the thin films both during and after growth. Our studies have shown both compounds form good quality single crystals when grown on an MBE-GaAs(100) surface.
- Research Organization:
- Rutgers-the State Univ., New Brunswick, NJ (United States)
- OSTI ID:
- 111261
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1993
- Country of Publication:
- United States
- Language:
- English
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