arXiv subjects

V. Jovanovic

Publications and source records attributed to V. Jovanovic.

5 recordsLinked to original sources

arXiv2010

Strain determination in the Si channel above a single SiGe island inside a field effect transistor using nanobeam x-ray diffraction

SiGe islands are used to induce tensile strain in the Si channel of Field Effect Transistors to achieve larger transconductance and higher current driveabilities. We report on x-ray diffraction experiments on a single fully-processed and functional device with a TiN+Al gate stack and source, gate, and drain contacts in place. The strain fields in the Si channel were explored using an x-ray beam focused to 400 nm diameter combined with finite element simulations. A maximum in-plane tensile strain of about 1% in the Si channel was found, which is by a factor of three to four higher than achievable for dislocation-free tensile strained Si in state-of-the-art devices.

cond-mat.mes-hall↗

arXiv2010

Penetration depth of electron-doped-infinite-layer Sr$_{0.88}$La$_{0.12}$CuO$_{2+x}$ thin films

The in-plane penetration depth of Sr$_{0.88}$La$_{0.12}$CuO$_{2+x}$ thin films at various doping obtained from oxygen reduction has been measured, using AC susceptibility measurements. For the higher doping samples, the superfluid density deviates strongly from the s-wave behavior, suggesting, in analogy with other electron-doped cuprates, a contribution from a nodal hole pocket, or a small gap on the Fermi surface such as an anisotropic s-wave order parameter. The low value of the superfluid densities, likely due to a strong doping-induced disorder, places the superconducting transition of our samples in the phase-fluctuation regime.

cond-mat.supr-con↗

arXiv2009

Maximum likelihood estimation of cloud height from multi-angle satellite imagery

We develop a new estimation technique for recovering depth-of-field from multiple stereo images. Depth-of-field is estimated by determining the shift in image location resulting from different camera viewpoints. When this shift is not divisible by pixel width, the multiple stereo images can be combined to form a super-resolution image. By modeling this super-resolution image as a realization of a random field, one can view the recovery of depth as a likelihood estimation problem. We apply these modeling techniques to the recovery of cloud height from multiple viewing angles provided by the MISR instrument on the Terra Satellite. Our efforts are focused on a two layer cloud ensemble where both layers are relatively planar, the bottom layer is optically thick and textured, and the top layer is optically thin. Our results demonstrate that with relative ease, we get comparable estimates to the M2 stereo matcher which is the same algorithm used in the current MISR standard product (details can be found in [IEEE Transactions on Geoscience and Remote Sensing 40 (2002) 1547--1559]). Moreover, our techniques provide the possibility of modeling all of the MISR data in a unified way for cloud height estimation. Research is underway to extend this framework for fast, quality global estimates of cloud height.

stat.AP↗

arXiv2008

Magnetoresistance and Hall effect in e-doped superconducting SrLaCuO thin films

We have epitaxially grown c-axis oriented SrxLa1-xCuO2 thin films by rf sputtering on KTaO3 substrates with x = 0.12. The as-grown deposits are insulating and a series of superconducting films with various Tc(R=0) up to 26 K have been obtained by in-situ oxygen reduction. Transport measurements in the ab plane of these samples have been undertaken. We report original results on the temperature dependence of the Hall effect and on the anisotropic magnetoresistance (T > Tc). We discuss the magnitude of upper critical fields and anisotropy, the Hall effect, which presents changes of sign indicative of the existence of two types of carriers, the normal state magnetoresistance, negative in parallel magnetic field, a possible signature of spin scattering. These properties are compared to those of hole-doped cuprates, such as BiSr(La)CuO with comparable Tc.

cond-mat.supr-con↗

arXiv2008

Influence of oxygen reduction on the structural and electronic properties of electron-doped Sr1-xLaxCuO2 thin films

Single phase, c-axis oriented, e-doped, Sr1-xLaxCuO2 thin films were epitaxially grown on KTaO3 and DyScO3 substrates by reactive rf sputtering. As-grown films being insulating due to oxygen excess, oxygen reduction is necessary to observe superconductivity. Two different procedures were employed to reach superconductivity. On one hand an in-situ reduction process was conducted on a series of films deposited on both types of substrates. On the other hand, an ex-situ reduction procedure was performed sequentially on a single film deposited on DyScO3. The study of the influence of oxygen reduction on the structural and electronic properties of the thin films is presented and discussed.

cond-mat.supr-con↗