Effect of dislocations in relaxed MBE SiGe layers on the electrical behavior of Si/SiGe heterostructures

Defects in Si/SiGe heterostructures and electrical behavior thereof have been studied. Misfit dislocations were observed in the epitaxial layers using cross-sectional transmission electron microscopy. These defects cause anomalies in the electrical behavior. It has been shown that, in spite of anomalies, the electrical measurements provide useful and reliable information on the structures.Исследованы дефекты в гетероструктурах Si/SiGe и их электрические характеристики. В эпитаксиальных слоях методом просвечивающей электронной микроскопии поперечных сечений обнаружены дислокации несоответствия. Эти дефекты вызывают аномалии в электрических характеристиках. Показано, что, несмотря на эти аномалии, электрические измерения обеспечивают полезную и надежную информацию о структурах.Досліджєно дефекти у гетероструктурах Si/SiGe та їх єлєктричні характеристики. В епітаксиальних шарах методом просвічувальної електронної мікроскопії поперечних перерізів виявлено дислокації невідповідності. Ці дефекти спричиняють аномалії в електричних характеристиках. Показано, що, незважаючи на ці аномалії, електричні вимірювання забезпечують корисну та надійну інформацію про структури

Model independent X-ray standing wave analysis of periodic multilayer structures

We present a model independent approach for the analysis of X-ray fluorescence yield modulated by an X-ray standing wave (XSW), that allow a fast reconstruction of the atomic distribution function inside a sample without fitting procedure. The approach is based on the direct regularized solution of the system of linear equations that characterizes the fluorescence yield. The suggested technique was optimized for, but not limited to, the analysis of periodic layered structures where the XSW is formed under Bragg conditions. The developed approach was applied to the reconstruction of the atomic distribution function for LaN/BN multilayers with 50 periods of 43 angstrom thick layers. The object is especially difficult to analyze with traditional methods, as the estimated thickness of the interface region between the constituent materials is comparable to the individual layer thicknesses. However, using the suggested technique, it was possible to reconstruct width of the La atomic distribution showing that the La atoms stay localized within the LaN layers and interfaces and do not diffuse into the BN layer. The analysis of the reconstructed profiles showed that the positions of the center of the atomic distribution function can be estimated with an accuracy of 1 angstrom. (C) 2014 AIP Publishing LLC