Occurrence of Hysteresis like behavior of resistance of Sb2Te3Sb_2 Te_3 film in heating-cooling cycle

Experimental observations of a peculiar behavior observed on heating and cooling ${\rm Sb_2Te_3}$ films at different heating and cooling rate are detailed. The film regained its original resistance, forming a closed loop, on the completion of the heating-cooling cycle which was reproducible for identical conditions of heating and cooling. The area enclosed by the loop was found to depend on (i) the thickness of the film, (ii) the heating rate, (iii) the maximum temperature to which film was heated and (iv) the cooling rate. The observations are explained on basis of model which considers the film to be a resultant of parallel resistances. The film's finite thermal conductivity gives rise to a temperature gradient along the thickness of the film, due to this and the temperature coefficient of resistance, the parallel combination of resistance changes with temperature. Difference in heating and cooling rates give different temperature gradient, which explains the observed hysteresis.Comment: 21 pages and 10 figure

Effect of Plasma Irradiation on CdI2Cd I_2 films

The effect of plasma irradiation is studied systematically on a 4H polytype (002) oriented ${\rm CdI_2}$ stoichiometric film having compressive residual stress. Plasma irradiation was found to change the orientation to (110) of the film at certain moderate irradiation distances. A linear decrease in grain size and residual stress was observed with decreasing irradiation distance (or increasing ion energy) consistent with both structural and morphological observations. The direct optical energy gap ${\rm E_g}$ was found to increase linearly at the rate ${\rm 15\mu eV/atm}$ with the compressive stress. The combined data of present compressive stress and from earlier reported tensile stress show a consistent trend of ${\rm E_g}$ change with stress. The iodine-iodine distance in the unit cell could be responsible for the observed change in ${\rm E_g}$ with stress.Comment: 13 pages and 10 fi

Study of CdI2{\rm CdI_2} nanocrystals dispersed in amorphous Sb2S3{\rm Sb_2S_3} matrix

Crystalline nanoparticles of cadmium iodide where suspended in the amorphous matrix of antimony trisulphide. Both materials are layered structured and have large band-gaps however cadmium iodide exhibits polytypism, i.e. it exists in various different crystalline states. Different crystalline states are marked by wholely different dielectric constants which give rise to sharp surface plasmon resonance (SPR) peaks in the UV-visible. The manuscript details the variation in SPR's with heat-treatment of the films.Comment: 10 pages 8 figures submitted to PR

Types of Nonlinear Interactions between Plasmonic-Excitonic Hybrids

The unique ability of plasmonic structures to concentrate and manipulate photonic signals in deep sub-wavelength domain provides new efficient pathways to generate, guide, modulate and detect light. Due to collective oscillations exhibited by the conducting electrons of metallic nanoparticles, their local fields can be greatly enhanced at the localized surface plasmon resonance (LSPR). Hence, they offer a versatile platform, where localized surface plasmons can be tuned over a broad range of wavelengths by controlling their shape, size and material properties. It has been realized that plasmonic excitations can strengthen nonlinear optical effects in three ways. First, the coupling between the incident beam of light and surface plasmons results in a strong local confinement of the electromagnetic fields, which in turn enhances the optical response. Second, the sensitivity of plasmonic excitations toward the dielectric properties of the metal and the surrounding medium forms the basis for label-free plasmonic sensors. Finally, the excitation and relaxation dynamics of plasmonic nanostructures responds to a timescale of femtoseconds regime, thus allowing ultrafast processing of the incident optical signals. This chapter aims to discuss all the aforementioned interactions of plasmons and their excitonic hybrids in detail and also represent a glimpse of their experimental realizations