ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Electrical activation and structural defects in lattice-mismatched InGaAs/GaAs heterostructures are studied using the capacitance-voltage method, deep-level transient spectroscopy, and cross-sectional transmission electron microscopy. Confinement of structural defects is observed in an In0.2Ga0.8As/GaAs heterostructure with a relaxed InGaAs layer thicker than the thickness of the critical layer. When In composition is 0.2, where the lattice mismatch is 1.4% between InGaAs and GaAs, a two-dimensional growth mode dominates. Misfit dislocations are formed and conduction electrons are depleted only near the InGaAs/GaAs interface. Carrier depletion is related to an electron trap with an activation energy of 0.395 eV and a capture cross section of 1×10−16 cm2 induced by deformation. Electrical evaluations show that electrical activity in the InGaAs layer does not degrade by interfacial dislocations. Therefore, a good-quality InGaAs layer is provided though the thin layer near the interface is of poor quality. These results indicate that elastic strain is not large enough in this system for dislocations to rise to the surface. In an In0.4Ga0.6As/In0.2Ga0.8As/GaAs heterostructure, however, dislocation confinement is imperfect in spite of similar lattice mismatches between each of the interfaces. In this structure, threading dislocations rise into the epitaxial layer not only from the In0.4Ga0.6As/In0.2Ga0.8As interface but also from the In0.2Ga0.8As/GaAs interface. This indicates that dislocations can be generated in the layer that had already been formed during the growth of an upper layer.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.355068
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