Surface and interface states on GaAs(110): Effects of atomic and electronic rearrangements
The electronic and atomic structure of the (110) surfaces of III--V semiconductors were studied. This paper briefly reviews new developments and points out areas where agreement has been found between various experimental results presented in the literature. Particular attention is focused on the large surface rearrangement which takes place on the (110) GaAs surface and effects of the strain which may be produced in joining this rearranged surface layer to the rest of GaAs crystal. It is pointed out that this may lead to variations in the surface rearrangement which can produce variations in the valence electronic structure at the surface. Such variations are shown in experimental energy distribution curves obtained by the photoemission technique which samples principally the last two molecular layers. It is further shown that surprisingly small amounts of chemisorbed oxygen can produce first-order effects in the valence-band electronic structure. On all GaAs (110) surfaces studied, a phaselike transformation was observed with a few hundredths of a monolayer coverage of chemisorbed oxygen. Near this coverage, the Ga 3d exciton structure disappears and the oxygen uptake increases significantly. On certain samples, first-order changes in the valence-band electronic structure were observed at a coverage of a hundredth of a monolayer or lower. These transformations are discussed in terms of the electronic and atomic configurations at the surface. Experimental data showing As and Ga 3d chemical shifts for oxidation as well as chemisorption are also presented and used to point out difficulties to be expected in passivating practical surfaces. In particular, the effect of mixed As and Ga oxides, the desirability of bonding passivating layers to the GaAs through As bonds, and the effect of strain-induced interface states are discussed.
- Research Organization:
- Department of Electrical Engineering, Stanford Electronics Laboratories, Stanford University, Stanford, California 94305
- OSTI ID:
- 7218812
- Journal Information:
- J. Vac. Sci. Technol.; (United States), Vol. 14:4
- Country of Publication:
- United States
- Language:
- English
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GALLIUM ARSENIDES
ELECTRONIC STRUCTURE
PASSIVATION
ARSENIC OXIDES
CHEMICAL SHIFT
CHEMISORPTION
D STATES
EXCITONS
GALLIUM OXIDES
INTERFACES
LAYERS
OXIDATION
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CHALCOGENIDES
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ENERGY LEVELS
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QUASI PARTICLES
SEPARATION PROCESSES
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