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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.


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Calculated (200) DF contrast function C200 for InxGa1-xAs (dash and dot line), GaAs1-yPy(solid line) and InxGa1-xAs1-yPywith x = 0.1 (dash line) (see text).
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Figure 3: Calculated (200) DF contrast function C200 for InxGa1-xAs (dash and dot line), GaAs1-yPy(solid line) and InxGa1-xAs1-yPywith x = 0.1 (dash line) (see text).

Mentions: Computed plots of C200 for InxGa1-xAs and GaAs1-yPy are given in Figure 3. These plots show that these two alloys look darker than GaAs for x < 0.437 and y < 0.707, respectively. InxGa1-xAs1-yPy is also darker than GaAs for x < 0.437 and y < 0.707 as is seen by similar plots; by way of example, only the plot for InxGa1-xAs1-yPy with x = 0.1 is shown in Figure 3. No other alloy has C200 < 1. Though (200) DF can clearly tell which alloy had formed in place of the nominal GaAs QW at the inverted GaAs-on-InGaP interface, no exact estimation of the composition is straightforward because of the square dependence of C200 on the composition and the indication of just a composition range.


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)

Calculated (200) DF contrast function C200 for InxGa1-xAs (dash and dot line), GaAs1-yPy(solid line) and InxGa1-xAs1-yPywith x = 0.1 (dash line) (see text).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Calculated (200) DF contrast function C200 for InxGa1-xAs (dash and dot line), GaAs1-yPy(solid line) and InxGa1-xAs1-yPywith x = 0.1 (dash line) (see text).
Mentions: Computed plots of C200 for InxGa1-xAs and GaAs1-yPy are given in Figure 3. These plots show that these two alloys look darker than GaAs for x < 0.437 and y < 0.707, respectively. InxGa1-xAs1-yPy is also darker than GaAs for x < 0.437 and y < 0.707 as is seen by similar plots; by way of example, only the plot for InxGa1-xAs1-yPy with x = 0.1 is shown in Figure 3. No other alloy has C200 < 1. Though (200) DF can clearly tell which alloy had formed in place of the nominal GaAs QW at the inverted GaAs-on-InGaP interface, no exact estimation of the composition is straightforward because of the square dependence of C200 on the composition and the indication of just a composition range.

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