Angular dependence of grazing-incidence x-ray scattering and Ge Ka fluorescence yield were measured for buried ultrathin Ge layers grown on bulk Si by molecular beam epitaxy. Results obtained for samples with different Ge layer thickness are compared. The data reveal information on microstructures in these layered materials in terms of the average interfacial roughness, correlation lengths of h...

An extensive ice body is buried under less than 20 cm to several meters of debris in Beacon Valley (Dry Valleys, Antarctica). The thermal behavior of the upper 20 m of permafrost, including the annually freezing and thawing surface (active layer) in this region of low relative humidity and very low annual precipitation, has great scientific interest. Distinctly different behavior from wet, arct...

A two-dimensional (2-D) finite-difference model for elastic waves in the ground has been developed. The model uses the equation of motion and the stress-strain relation, from which a first-order stress-velocity formulation is obtained. The resulting system of equations is discretized using centered finite-differences. A perfectly matched layer surrounds the discretized solution space and absorb...

A three-terminal spectroscopy that probes both subsurface energy barriers and interband optical transitions in a semiconductor heterostructure is demonstrated. A metal-base transistor with a unipolar p-type semiconductor collector embedding InAs/GaAs quantum dots QDs is studied. Using minorityor majority-carrier injection, ballistic electron emission spectroscopy and its related hot-carrier sca...

In this work we investigated the diffusion and clustering of supersaturated substitutional carbon 200nm thick SiGeC layers buried under a silicon cap layer of 40nm. The samples were annealed in inert (N2) or oxidizing (O2) ambient at 850°C for times ranging from 2 to 10 hours. The silicon self-interstitial (I) flux coming from the surface under oxidation enhances the C diffusion with respect to...

In this work, we present results on the formation of vertical molecule structures formed by two vertically aligned InAs quantum dots (QD) in which a deliberate control of energy emission is achieved. The emission energy of the first layer of QD forming the molecule can be tuned by the deposition of controlled amounts of InAs at a nanohole template formed by GaAs droplet epitaxy. The QD of the s...