Figure 1 Schematic view of the PSi-based layer-transfer process. In particular, strain in the whole PSi stack and surface roughness of the LPL are two major factors that drastically influence the epitaxial growth because of their role in the creation of dislocations, stacking faults, and other crystalline defects during epitaxy. Firstly, the lattice parameter of the as-etched PSi is in fact slightly larger than that of Si. This mismatch results in a contraction of the crystal planes of PSi in order to attain the same interatomic spacing as the Si substrate. As a result, a slight out-of-plane expansion (or tensile strain) is produced in PSi [4]. This tensile

strain increases with porosity and the mean pore radius [4]. X-ray diffraction (XRD), especially in the high-resolution configuration (HR-XRD) was employed to detect this CX-4945 chemical structure strain. Early attempts to determine strain in PSi were carried out by Barla et al. using a double-crystal diffractometer with a single silicon monochromator [4]. Afterward strain click here characterization using HR-XRD

based on a four-reflection Ge monochromator becomes the most common [5]. Secondly, considering surface roughness, it is well known that crystalline defects inside epitaxial layers increase with the surface selleck chemical roughness of the seed layer. Both strain and roughness of the seed layer can be reduced by optimizing the PSi stack, which is by fine-tuning the layer thicknesses and annealing time before epitaxy. Previously, Sivaramakrishnan Radhakrishnan et al. used micro-Raman measurements on annealed PSi to show that tuning the porosity and thickness of the LPL can result in a smoother seed surface with a lower residual stress distribution in the PSi stack. Subsequently, this leads to a lower epi-foil defect density [3]. Alternatively, Martini et al. used high-resolution profilometry (HRP) measurements to show how to obtain smoother annealed seed layers, which ALOX15 in turn result in a higher epitaxy quality [6]. In addition, G. Lamedica et. al showed that lattice deformation of both PSi layer and Si epitaxial layers grown on PSi strongly depends on the PSi porosity. They also showed that the epilayers grown

on double-porosity layers have a high quality compared to films grown on n+-type single crystal Si substrates [7]. In this work, we present a fundamental investigation for the effect of the thickness of PSi and of its sintering time on strain and surface roughness. Strain is monitored on mono- and double-PSi layers by HR-XRD and surface roughness by HRP. In the first part, we study the impact of PSi thickness and present a model to support our observation of the strain reduction with a thicker LPL in a double layer of PSi. In the second part, we underline the change in strain type upon annealing, and then emphasize the antagonistic impacts of annealing time on strain and surface roughness. We correlate the strain reduction of the whole PSi stack to the HPL morphology, which is with the disappearance of the interconnections.