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Shiv Nadar University

(SoNS) School of Natural Sciences

Squeezed states for parabosons are constructed since we know that a parabose oscillator can be parametrized in terms of bosonic operators. We also discuss some of their important properties.

Physics

World University root node

Modern Physics Letters A

Squeezed states for parabosons

Exploiting the Lax form of the Korteweg-de Vries equation, we determine the whole set of its symmetry operators and relate them to conserved quantities. We also study a KdV supersymmetric version and put in evidence its even (bosonic) and odd (fermionic) symmetries. We then get the Lie superalgebra characterizing this supersymmetric nonlinear equation. © World Scientific Publishing Company.

International Journal of Modern Physics A

Generating symmetry operators for the KdV equation and seeking their supersymmetric generalizations

The results of MeV Kr+ ion-beam mixing of Au in amorphous metallic alloy Fe78B13Si9 at room temperature for various doses are presented. The mixing rate found experimentally does not correlate with prediction of current phenomenological models which consider the influence of ballistic and thermodynamic parameters of the mixing.

Radiation Physics and Chemistry

MeV ion beam mixing of Au in Fe78B13Si9 amorphous metallic alloy

This paper reports on the atomic transport occurring across the interface of Cu/Ge and Co/Ge layers leading to the synthesis of Cu3Ge and Co2Ge phases under MeV Kr and Ar ion irradiations. These phases have potential applications in modern semiconductor device technology. The marker experiments show that in the case of Cu/Ge systems both Cu and Ge are mobile but Cu is the dominant moving species. On the other hand, in the case of the Co/Ge system only Ge atoms are mobile. The atomic movements during ion irradiation in these two systems have been explained on the basis of distribution of defect density and effects of thermodynamic forces. © 1998 Elsevier Science S.A. All rights reserved.

Thin Solid Films

Atomic transport in Cu/Ge and Co/Ge systems during ion-beam mixing

We have studied trapping kinetics of defects during carrier capture in heavily damaged silicon, where damage was induced by MeV heavy ions at doses near but below the amorphization threshold. Using spectroscopic junction transient measurements, we provide unambiguous evidence of charge redistribution between defects. These results imply that changes in the occupancy of gap states are responsible for the deepening of emission energies with filling time, as is commonly observed in transient experiments in disordered silicon. This is in contrast to its usual explanation in terms of deepening of energy states due to hierarchical defect relaxation. © 1998 The American Physical Society.

Physical Review B - Condensed Matter and Materials Physics

Charge redistribution among defects in heavily damaged silicon

The propagation of the carbon plumes in argon atmosphere used for film growth by pulsed laser ablation deposition (PLAD) is studied using ion probe. Spatial and angle resolved analysis of plasma parameters as a function of argon gas pressure is presented. The electron temperature is strongly dependent on the angle with target surface normal as well as the distance from the target surface. The forward directed nature of the PLAD process is strongly influenced by the pressure of the ambient gas. The plasma parameters are used to explain the effect of ambient gas pressure on the characteristics of the deposited film.

International Journal of Modern Physics B

Ion probe diagnostics of laser ablated plumes for thin carbon films deposition

An isothermal spectroscopic technique called time analyzed transient spectroscopy (TATS) in the constant capacitance (CC) mode has been used to characterize electrically active defects in the MeV Ar+ implanted silicon. The problems associated with high defect density and the presence of damaged region in the as-implanted material are overcome by CC-TATS method. The CC-TATS spectra of the as-implanted sample shows two positive peaks and an attendant negative peak. Two distinct traps have also been identified using thermally stimulated capacitance method modified to operate in constant capacitance mode. Variable pulse width measurements using CC-TATS show exponential capture kinetics in contrast to extremely slow capture observed in conventional deep level transient spectroscopy (DLTS) experiment. The results indicate that trapping behaviour is due to point-like defects associated with extended defects such as dislocation and stacking fault.

Fulltext

Bulletin of Materials Science

Characterization of deep level defects in Si irradiated with Me V Ar + ions using constant capacitance time analyzed transient spectroscopy

The copper germanide phase Cu3Ge which is emerging as an alternative material for making contacts and interconnects for semiconductor industry has been produced across the interface of Cu/Ge bilayers by ion beam mixing at room temperature using 1 Me V Ar ions. The dose dependence of the thickness of the mixed region shows a diffusion controlled mixing process. The experimental mixing rate and efficiency for this phase are 5.35 nm4 and 10.85 nm5keV respectively. At doses above 8 × 1015 Ar/cm2 the formation and growth of another copper rich phase Cu5Ge has been observed. The present theoretical models are inadequate to explain the observed experimental mixing rate.

Ar ion induced copper germanide phase formation at room temperature

In view of the ever-growing importance of ion beams in optical material processing, this letter reports room-temperature MeV He+ ion irradiation induced depletion of hydrogen from single crystalline potassium dihydrogen phosphate (KH2PO4 or KDP) which has wide applications as a nonlinear optical material in optoelectronics technology. Irradiations have been performed using 1.5 MeV He+ ions up to a maximum dose of 2.4 × 1015 ions/cm2. Simultaneously, hydrogen profiling has been done by detecting the elastically recoiled H atoms. Bare KDP crystals show a hydrogen loss of 72% at the maximum dose whereas Au coated samples show that 60 Å of Au layer acts as a barrier to considerably reduce hydrogen depletion from KDP. A possible explanation of these phenomena is suggested.

Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Hydrogen depletion from KH2PO4 under He+ ion bombardment

We have studied electrically active defects in buried layers, produced by heavy ion implantation in silicon, using both conventional deep level transient spectroscopy (DLTS) and an isothermal spectroscopic technique called time analyzed transient spectroscopy operated in constant capacitance mode (CC-TATS). We show that CC-TATS is a more reliable method than DLTS for characterization of the heavily damaged buried layers. The major trap produced in the buried layers in p-type Si by MeV Ar+ implantation is found to have an energy level at Ev+0.52 eV. This trap, believed to be responsible for compensation in the damaged layer, shows exponential capture dynamics. We observed an unusually high thermal activation energy for capture, which is attributed to a macroscopic energy barrier for carriers to reach the buried layer. We observe two other majority carrier traps, and also a minority carrier trap possibly due to inversion within the depletion layer. © 1997 American Institute of Physics.