Chemical characterization of extra layers at the interfaces in MOCVD InGaP/GaAs junctions by electron beam methods
1 CNR-IMEM Institute, Parco Area delle Scienze 37/A, 43010 Parma, Italy
2 Ioffe Physical Technical Institute, 194021 Polytekhnicheskaya 26, Saint-Petersburg, Russia
Nanoscale Research Letters 2011, 6:194 doi:10.1186/1556-276X-6-194Published: 3 March 2011
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.