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Chemical characterization of extra layers at the interfaces in MOCVD InGaP/GaAs junctions by electron beam methods.

Frigeri C, Shakhmin AA, Vinokurov DA, Zamoryanskaya MV - Nanoscale Res Lett (2011)

Bottom Line: A CL emission peak different from that of the QW was detected.By using HAADF, it is found that the GaAs QW does not exist any longer, being replaced by extra interlayer(s) that are different from GaAs and InGaP because of atomic rearrangements at the interface.The nature and composition of the interlayer(s) are determined by HAADF.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNR-IMEM Institute, Parco Area delle Scienze 37/A, 43010 Parma, Italy. frigeri@imem.cnr.it.

ABSTRACT
Electron beam methods, such as cathodoluminescence (CL) that is based on an electron-probe microanalyser, and (200) dark field and high angle annular dark field (HAADF) in a scanning transmission electron microscope, are used to study the deterioration of interfaces in InGaP/GaAs system with the GaAs QW on top of InGaP. A CL emission peak different from that of the QW was detected. By using HAADF, it is found that the GaAs QW does not exist any longer, being replaced by extra interlayer(s) that are different from GaAs and InGaP because of atomic rearrangements at the interface. The nature and composition of the interlayer(s) are determined by HAADF. Such changes of the nominal GaAs QW can account for the emission observed by CL.

No MeSH data available.


Related in: MedlinePlus

Plot of the calculated ratio R between the HAADF intensities of In0.15Ga0.85As1-yPy and GaAs. Inset is the top left part of the plot.
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Figure 6: Plot of the calculated ratio R between the HAADF intensities of In0.15Ga0.85As1-yPy and GaAs. Inset is the top left part of the plot.

Mentions: Figure 6 is a worked-out example of the procedure used to extract information on the nature and composition of sublayers 1 and 2. Figure 6 is the plot of the calculated intensity ratio between In0.15Ga0.85As1-yPy and GaAs. It shows that the experimental value of Rexp = 1.02 for sublayer 1 can be accounted for if the layer is In0.15Ga0.85As0.81P0.19. A similar plot for InxGa1-xAs to GaAs shows that In0.03Ga0.97As also fits the experimental result Rexp = 1.02. The same procedure applied using the In0.51Ga0.49P and Al0.26Ga0.74As layers as standards leads to the same results for the stoichiometric indices, within 5%. By taking average values, it turns out that the sublayer 1 can be either In0.15Ga0.85As0.80P0.20 or In0.023Ga0.977As. As for sublayer 2 of the nominal GaAs QW, it results in either In0.05Ga0.95As0.84P0.16 or GaAs0.91P0.09 by the same procedure.


Chemical characterization of extra layers at the interfaces in MOCVD InGaP/GaAs junctions by electron beam methods.

Frigeri C, Shakhmin AA, Vinokurov DA, Zamoryanskaya MV - Nanoscale Res Lett (2011)

Plot of the calculated ratio R between the HAADF intensities of In0.15Ga0.85As1-yPy and GaAs. Inset is the top left part of the plot.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211250&req=5

Figure 6: Plot of the calculated ratio R between the HAADF intensities of In0.15Ga0.85As1-yPy and GaAs. Inset is the top left part of the plot.
Mentions: Figure 6 is a worked-out example of the procedure used to extract information on the nature and composition of sublayers 1 and 2. Figure 6 is the plot of the calculated intensity ratio between In0.15Ga0.85As1-yPy and GaAs. It shows that the experimental value of Rexp = 1.02 for sublayer 1 can be accounted for if the layer is In0.15Ga0.85As0.81P0.19. A similar plot for InxGa1-xAs to GaAs shows that In0.03Ga0.97As also fits the experimental result Rexp = 1.02. The same procedure applied using the In0.51Ga0.49P and Al0.26Ga0.74As layers as standards leads to the same results for the stoichiometric indices, within 5%. By taking average values, it turns out that the sublayer 1 can be either In0.15Ga0.85As0.80P0.20 or In0.023Ga0.977As. As for sublayer 2 of the nominal GaAs QW, it results in either In0.05Ga0.95As0.84P0.16 or GaAs0.91P0.09 by the same procedure.

Bottom Line: A CL emission peak different from that of the QW was detected.By using HAADF, it is found that the GaAs QW does not exist any longer, being replaced by extra interlayer(s) that are different from GaAs and InGaP because of atomic rearrangements at the interface.The nature and composition of the interlayer(s) are determined by HAADF.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNR-IMEM Institute, Parco Area delle Scienze 37/A, 43010 Parma, Italy. frigeri@imem.cnr.it.

ABSTRACT
Electron beam methods, such as cathodoluminescence (CL) that is based on an electron-probe microanalyser, and (200) dark field and high angle annular dark field (HAADF) in a scanning transmission electron microscope, are used to study the deterioration of interfaces in InGaP/GaAs system with the GaAs QW on top of InGaP. A CL emission peak different from that of the QW was detected. By using HAADF, it is found that the GaAs QW does not exist any longer, being replaced by extra interlayer(s) that are different from GaAs and InGaP because of atomic rearrangements at the interface. The nature and composition of the interlayer(s) are determined by HAADF. Such changes of the nominal GaAs QW can account for the emission observed by CL.

No MeSH data available.


Related in: MedlinePlus