Interface roughness in strained Si/SiGe multilayers

Diffuse x-ray reflection from a SiGe/Si multilayer grown pseudomorphically on slightly miscut Si(OO I) substrates has been studied theoretically and experimentally. In the framework of the Distorted-Wave Born Approximation (DWBA). we demonstrated that the distribution of the diffusely scattered intensity gives conclusive information on both the amount and the in-plane and inter-plane correlation properties of the interface roughness. The best model for the description of the interface-morphology was found to be a combination of a two-level model and a staircase model

Enhanced Lithiation Cycle Stability of ALD-Coated Confined a‑Si Microstructures Determined Using In Situ AFM

Microfabricated amorphous silicon (a-Si) pits ∼4 μm in diameter and 100 nm thick were fabricated to be partially confined in a nickel (Ni) current collector. Corresponding unconfined pillars were also fabricated. The samples were coated with 1.5, 3, or 6 nm of Al₂O₃ ALD. These samples were tested in electrolytes of 3:7 by weight ethylene carbonate:ethyl methyl carbonate (EC:EMC) with 1.2 M LiPF₆ salt with and without 2% fluoroethylene carbonate (FEC) and in a pure FEC electrolyte with 10 wt % LiPF₆. The samples were imaged with an atomic force microscope during electrochemical cycling to evaluate morphology evolution and solid electrolyte interphase (SEI) formation. The partially confined a-Si structures had superior cycle efficiency relative to the unconfined a-Si pillars. Additionally, samples with 3 nm of ALD achieved higher charge capacity and enhanced cycle life compared to samples without ALD, demonstrated thinner SEI formation, and after 10 cycles at a 1 C rate remained mostly intact and had actually decreased in diameter. Finally, the samples with 3 nm of ALD had better capacity retention in the baseline 3:7 EC:EMC than in either of the FEC containing electrolytes

Structural characterization of self-assembled Ge-dots by x-ray diffraction and reflection

Self-organized Ge-dots on (OOI)-oriented Si-substrates have been studied using twodimensionally resolved high resolution x-ray diffraction and reflectivity. The degree of the vertical correlation of the dot positions ("stacking") has been derived as well as a lateral ordering of the dots in a (disordered) square array with main axes parallel to [100] and [010]