Sputtering Codeposition and Metal-Induced Crystallization to Enhance the Power Factor of Nanocrystalline Silicon.

The power factor of highly boron-doped nanocrystalline Si thin films with controlled doping concentration is investigated. We achieve a high degree of tuning of boron content with a charge carrier concentration from 10 to 10/cm and with the electrical conductivity by varying the boron magnetron power from 10 to 60 W while maintaining the power of a SiB source constant during codeposition from two independent sputtering sources. Along with the increase in the electrical conductivity with increased boron doping, we observe a steady decrease in the Seebeck coefficient from 500 to 100 μV/K.

Micro-Kelvin Resolution at Room Temperature Using Nanomechanical Thermometry.

Ultrahigh sensitivity temperature measurement is becoming increasingly relevant for different scientific and technological fields from fundamental physics to high-precision engineering applications. Here, we demonstrate the use of a nanomechanical resonator-free standing silicon nitride membranes with thicknesses in the nanoscale-for room temperature thermometry reaching an unprecedented resolution of 15 μK. These devices were characterized by using an interferometric system at high vacuum, where there are only two possible mechanisms for heat transfer: thermal conductivity and radiation.

Deconvolution of Phonon Scattering by Ferroelectric Domain Walls and Point Defects in a PbTiO Thin Film Deposited in a Composition-Spread Geometry.

We present a detailed analysis of the temperature dependence of the thermal conductivity of a ferroelectric PbTiO thin film deposited in a composition-spread geometry enabling a continuous range of compositions from ∼25% titanium deficient to ∼20% titanium rich to be studied. By fitting the experimental results to the Debye model we deconvolute and quantify the two main phonon-scattering sources in the system: ferroelectric domain walls (DWs) and point defects. Our results prove that ferroelectric DWs are the main agent limiting the thermal conductivity in this system, not only in the stoichiometric region of the thin film ([Pb]/[Ti] ≈ 1) but also when the concentration of the cation point defects is significant (up to ∼15%).

Ferroelectric Domain Walls in PbTiO Are Effective Regulators of Heat Flow at Room Temperature.

Achieving efficient spatial modulation of phonon transmission is an essential step on the path to phononic circuits using "phonon currents". With their intrinsic and reconfigurable interfaces, domain walls (DWs), ferroelectrics are alluring candidates to be harnessed as dynamic heat modulators. This paper reports the thermal conductivity of single-crystal PbTiO thin films over a wide variety of epitaxial-strain-engineered ferroelectric domain configurations.

Enhanced antibody recognition with a magneto-optic surface plasmon resonance (MO-SPR) sensor.

A comparison between sensing performance of traditional SPR (Surface Plasmon Resonance) and magneto-optic SPR (MOSPR) transducing techniques is presented in this work. MOSPR comes from an evolution of traditional SPR platform aiming at modulating Surface Plasmon wave by the application of an external magnetic field in transverse configuration. Previous work demonstrated that, when the Plasmon resonance is excited in these structures, the external magnetic field induces a modification of the coupling of the incident light with the Surface Plasmon Polaritons (SPP).

Probing the electromagnetic field distribution within a metallic nanodisk.

A Co nanolayer is used as a local probe to evaluate the vertical inhomogeneous distribution of the electromagnetic (EM) field within a resonant metallic nanodisk. Taking advantage of the direct relation between the magneto-optical activity and the electromagnetic field intensity in the Co layer, it is shown that the nonuniform EM distribution within the nanodisk under plasmon resonant conditions has maximum values close to the upper and lower flat faces, and a minimum value in the middle.