[en] Photothermal beam deflection technique has been employed for the measurement of thermal diffusivity of different compositions of semiconducting amorphous Ge_xSe_100-x thin films. Slope from the tangential component of the deflection signal with the pump-probe offset is used to evaluate the numerical value of thermal diffusivity (α). The mirage signal is analysed using the phase method and the result of the measurement is verified using the amplitude method. The experiments are carried out using carbon tetrachloride as the coupling medium for two different modulation frequencies, both of which have yielded the same value of thermal diffusivity. The variation in thermal diffusivity of the samples with composition is also investigated and is explained on the basis of structural changes taking place in the glass network

[en] Low-resistivity (<0.1 Ω cm), p-type SiC layers of about 500 nm width and targeted acceptor concentrations of 1.5x10²⁰ cm^-3 and 5.0x10²⁰ cm^-3 were produced by the combination of high-dose (1.0 and 3.3x10¹⁶ cm^-2), multienergy (50-450 keV) Al⁺ ion implantation of 6H-SiC at -130 deg. C, ion-beam-induced crystallization with 500 keV, 5x10¹⁵ Si⁺ cm^-2 at 500 deg. C and subsequent furnace annealing at 1500 deg. C for 10 min. The implanted SiC layers have a nanocrystalline structure consisting of randomly oriented grains of mainly 3C-SiC. The electrical properties of the doped, nanocrystalline layers were investigated by sheet resistance and Hall measurements in dependence on temperature and compared with results from single-crystalline reference samples. In comparison with the standard doping process, the hole concentration at 50 deg. C is enhanced by more than one order of magnitude from 9.0x10¹⁷ cm^-3 to 1.6x10¹⁹ cm^-3 in the case of 1.5x10²⁰ Al cm^-3 and from 6.1x10¹⁸ cm^-3 to 8.0x10¹⁹ cm^-3 in the case of 5.0x10²⁰ Al cm^-3, respectively. It can be speculated that the loss of active Al acceptors by precipitation is reduced in the nanocrystalline layers and, therefore, the critical concentration for the formation of an impurity band can be achieved

[en] Short communication

[en] Short communication

[en] Investigations on the electrical activation in high dose Al⁺ ion implanted SiC have been carried out using spreading resistance depth profiling measurements. The spreading resistance data is used to obtain the depth profile of carrier concentration. The depth profile information obtained closely matches with TRIM profile. The results indicate the existence of optimum conditions in terms of ion dose and implantation temperature. (author)

[en] Ion irradiation of hydrocarbons is one of the methods for the preparation of amorphous hydrogenated carbon (a-C:H). We have investigated the near infrared absorption of polystyrene film subjected to ion irradiation with different doses of He⁺ and H⁺ions. Photothermal deflection spectroscopy (PDS) technique was used to record the absorption spectrum in the wavelength range 1.20μm to 2.0μm. The evolution of the various overtone and combination bands occurring in this range has been related to the changes taking place in the polystyrene structure. (author)

[en] Photoacoustic (Pa) technique is used to study glass transition and temperature dependence of thermal diffusivity in As_xTe_1-x glasses with 0.25 ≤ x ≤ 0.60. PA amplitude goes through a minimum and the phase shows a maximum at glass transition temperature T_g. The variation of thermal diffusivity with temperature shows sharp decrease near T_g. The variation of thermal diffusivity with composition shows maximum at x = 0.40 for all temperatures T ≤ T_g. (author)

[en] In this paper, we demonstrate pure, Gd-doped, and Gd/Li co-doped ZnO nanostructures for NO₂ gas sensing applications fabricated via the sol–gel spin coating route. The synthesized samples are examined through various characterization techniques to evaluate their physical and chemical properties. The gas sensing performance of all deposited samples was investigated at different temperatures (150–240 °C) towards 75 ppm of NO₂ gas. Among them, the Gd/Li co-doped ZnO sample shows remarkable NO₂ gas sensing performance of 55.18 at a working temperature of 210 °C. Also, the gas sensitivity of Gd/Li: ZnO towards various toxic gases, including Cl₂, NH₃, NO, and NO₂, were studied and appeared most selective towards NO₂ gas. A possible NO₂ gas sensing mechanism was discussed and correlated with structural, morphological, electrical, and spectral studies. (author)

[en] Indium oxide thin films were prepared by pulsed dc magnetron sputtering technique with no substrate heating. X-ray diffraction was used to investigate the structural properties and AFM was used to study the surface morphology gas sensing performance were conducted using a static gas sensing system. Room temperature gas sensing performance was conducted in range of 17 to 286 ppm. The sensitivity, response and recovery time of the sensor was also determined. (author)

[en] A detailed study of the implantation-induced damage in Si on sapphire, carried out by optical-absorption measurements extending from energies above the band gap down to energies far into the subgap region of Si, is presented. The changes induced in the optical band gap, band-edge slopes, and in the subgap features of the spectra are carefully described. The various stages of formation and quenching of divacancies were monitored as a function of implantation conditions and annealing cycles through their 1.8-μm absorption band. It is shown that the divacancies strongly affect the population of band-tail states and the annealing studies revealed that the progressive quenching of the divacancy band is followed by the appearance of another absorption band, characteristic of some intrinsic secondary defect, whose annealing behavior is similar to the one observed for the five-vacancy electron-paramagnetic-resonance spectrum. The study of the structural relaxation process in implanted a-Si gave indications that the process is indeed associated with annihilation of defects as well as average strain reduction in the material, in agreement with earlier indications. Finally, some common features, such as band-edge inverse-logarithmic slope values and subgap features, are found in annealed implanted crystalline and a-Si