Abstract
In order to reduce the dislocation density and improve the performance of high indium content In0.82Ga0.18As films, the design of double buffer layers has been introduced into the In0.82Ga0.18As/InP heterostructure. Compared with other buffer layer structures, we introduce an InP thin layer, which is the same as the substrate, into the In0.82Ga0.18As/InP heterostructure. The epitaxial layers and buffer layers were grown by the low-pressure metalorganic chemical vapor deposition (LP-MOCVD) method. In this study, the surface morphology and microstructures of the heterostructure were investigated by SEM, AFM, XRD and TEM. The residual strains of the In0.82Ga0.18As epitaxial layer in different samples were studied by Raman spectroscopy. The residual strain of the In0.82Ga0.18As epitaxial layer was decreased by designing double buffer layers which included an InP layer; as a result, dislocations in the epitaxial layer were effectively suppressed since the dislocation density was notably reduced. Moreover, the performance of In0.82Ga0.18As films was investigated using the Hall test, and the results are in line with our expectations. By comparing different buffer layer structures, we explained the mechanism of dislocation density reduction by using double buffer layers, which included a thin InP layer.
Highlights
The ternary III–V compounds Inx Ga1−x As (0 < x < 1) with features such as relatively high carrier density, wide direct band gap ranging from 0.35 to 1.42 eV, high reliability and radiation resistance [1,2,3,4,5], have wide applications in short-wave infrared photodetectors [6,7,8,9] and solar cells [10, 11]
High indium content Inx Ga1−x As (x = 0.82) detectors with a cut-off wavelength of more than 2 μm applied in aerospace imaging and spectroscopy attract more interest [12]
The lattice mismatch between the epitaxial layers and substrates strongly affects the performance of the In0.82 Ga0.18 As films
Summary
The ternary III–V compounds Inx Ga1−x As (0 < x < 1) with features such as relatively high carrier density, wide direct band gap ranging from 0.35 to 1.42 eV, high reliability and radiation resistance [1,2,3,4,5], have wide applications in short-wave infrared photodetectors [6,7,8,9] and solar cells [10, 11]. InP and GaAs substrates have been commonly used for the growth of Inx Ga1−x As films [13,14,15]. The lattice mismatch between the epitaxial layers and substrates strongly affects the performance of the In0.82 Ga0.18 As films. InP is often used as the preferred substrate material, the lattice mismatch is still too large to obtain a good In0.82 Ga0.18 As film. In order to obtain high quality In0.82Ga0.18As/InP (100) structures, the lattice defect formation due to misfit remains a major problem that needs to be solved. We that dislocation density be reducing in the epitaxial layer. Weexpected designed three different buffer layer structures for by the epitaxial layer growth. We designed three different buffer layer structures for comprehensive comprehensive comparison in order to verify our assumptions.
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