Influence of strain, specimen orientation and background estimation on composition evaluation of InAs/GaAs by TEM

On the incorporation of indium in InAs-based quantum structures

“…Another contribution to the error is caused by the thickness measurement because the boundaries of the projected WL are blurred, limiting the accuracy of the width measurement and the derived sample thickness. Apart from the intrinsic errors of CELFA [23], the In concentration should be measurable with a relative error of about 10 % using the suggested procedure with a more precisely known sample thickness and neglecting the fact that shape information along the electron-beam direction for a specific QD is not accessible. …”

“…These planes are oriented perpendicular to the buffer/QD-interface and less affected by distortions. More details on the accuracy of CELFA and sources of error can be found in [23]. Scanning transmission electron microscopy (STEM) with a high-angle annular dark-field (HAADF) detector was carried out using a ZEISS 922 Omega with a LaB 6 emitter to obtain composition sensitive (Z contrast) images.…”