Lattice imaging of antiphase boundaries in GaAs grown on Si
The growth of GaAs on Si has been recognized as a highly desirable technology goal for a number of years. However, the large lattice misfit between GaAs and Si and the problem of growing a polar crystal on a nonpolar substrate can result in a high density of lattice defects, including antiphase disorder. Our studies were carried out on GaAs grown by MOCVD on exactly oriented (100) Si wafers and by MBE on wafers tilted by 4{degrees} toward (110). In both these cases high densities of defects, mostly stacking faults and dislocations, were observed in cross-sectioned samples. Antiphase boundaries APB's were identified in both types of samples by Covergent Beam Electron Diffraction (CBED) patterns. For edge-on (110) APB's high resolution images were taken by the Atomic Resolution Microscopy. Antiphase boundaries showed a lattice image displacement of 0.14nm across the boundary. We have performed multislice calculations for the ARM conditions using the SHRLI program for the model structure of GaAs of up to 4nm thickness containing two APB's. The model is a pure antiphase boundary and does not include any displacement of atoms from ideal positions. We could show that antiphase boundaries can be unambiguously identified by high-resolution TEM combined with CBED. Lattice imaging of these boundaries can show a typical shift of the {l brace}111{r brace} planes across the boundary, if the sample thickness falls within a specific, narrow range. 6 refs., 3 figs.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5620376
- Report Number(s):
- LBL-24985; CONF-880841-25; ON: DE91014471
- Resource Relation:
- Conference: MAS/EMSA microbeam analysis conference, Milwaukee, WI (United States), 7-12 Aug 1988
- Country of Publication:
- United States
- Language:
- English
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