Investigation of Composition Uniformity in Thickness of GaInAsP Layers Grown on InP Substrates by Vapor-Phase Epitaxy
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GaInPAs/InP heterostructures grown by metalorganic chemical vapor-phase deposition at a temperature of 600°C and pressure of 0.1 bar are investigated. The thicknesses of the grown GaInAsP layers amount to about 1 μm. For Ga1 –xInxP1 –yAsy solid solutions with average compositions of x = 0.77–0.87 and y = 0.07–0.42, the variation in the content y of V-group atoms over the epitaxial-layer thickness by a value of Δy up to 0.1 atomic fractions in the sublattice of the V-group elements is revealed by secondary ion mass spectrometry. In most cases, a change in y occurs in the GaInAsP layer over a length to 200 nm from the InP heterointerface. In certain cases, y varies throughout the entire GaInPAs-layer thickness. For the epitaxial layers with satisfactory crystalline perfection, the value of Δy is less in the case of better lattice-matching between the GaInPAs epitaxial layer and the substrate. For GaInPAs layers strongly lattice-mismatched with the substrate and characterized by a low degree of crystalline perfection, the value of Δy is close to zero. All these facts enable us to assume that it is elastic deformations arising in the forming monolayer lattice-mismatched with the growing surface that affect the incorporation of V-group atoms into the forming crystalline lattice.
Keywords:vapor-phase epitaxy solid solutions heterostructures photovoltaic converters
We thank our colleague at the Ioffe Institute S.I. Troshkov for SEM images of the cleavage facets and sample surfaces.
The SIMS, SEM, and Camebax investigations were carried out using equipment of the Center of Multi-User Scientific Equipment “Material Science and Diagnostics for Advanced Technologies” (Ioffe Institute) supported by the Ministry of Education and Science of the Russian Federation (unique project identifier RFMEFI62117X0018).
CONFLICT OF INTEREST
The authors declare that they have no conflict of interest.
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