http://profdoc.um.ac.ir/articles/a/1015558.pdf

Fe-doped SnO2 transparent semi-conducting thin films deposited by spray pyrolysis technique: Thermoelectric and p-type conductivity properties

The feasibility of multilayered optical data storage was examined in SiO2 and Ge–SiO2 glasses by using a focused 800 nm, 120 fs, 200 kHz pulsed laser. The glasses are transparent in the wavelengths ranging from 300 to 1000 nm. After the irradiation with the 800 nm tightly focused femtosecond laser, a refractive-index bit was formed in the glasses. The relationships between the size of refractive-index bit versus average power and irradiation duration of the laser pulse have been examined. ESR spectra showed a significant increase in the concentration of SiE' and GeE' color centers in the laser irradiated glasses. Writing 3-dimensional refractive-index bit inside the transparent glasses based on a multi-photon absorption process is expected to become a useful method used to fabricate optical memory with both an ultra-high storage density and an ultra-high recording speed.

https://iopscience.iop.org/article/10.1143/JJAP.37.2263/pdf

Three-Dimensional Optical Memory Using Glasses as a Recording Medium through a Multi-Photon Absorption Process

Handbook of thin film technology

The compositional dependence of the thermal properties of SbxSe100−x melt quenched glasses (0.01 < x < 25 at.%) has been studied. Modulated temperature differential scanning calorimetry technique has been applied to determine the thermal properties of Se-rich SbxSe100−x chalcogenide glasses in the glass transition and crystallization regions. The reversing and non-reversing heat flows through the glass transformations were measured during both heating and cooling scans. Tg (glass transition), ΔHg (relaxation enthalpy), Cp (specific heat capacity), ΔCp (change in Cp at Tg), ΔHc (crystallization enthalpy), Tp (peak crystallization rate temperature) and Tc (crystallization onset temperature) which determine the thermal events in the glass were calculated from the experimental curves. Some of the structurally controlled parameters such as Tg, Cp, and Tc − Tg reveal local extrema when the Sb–Se glass system reaches 1 at.% Sb and 15 at.% Sb approximate concentrations, where the glass forming ability was also maximal. We discuss the results in terms of possible dimensional structural changes, `size effect' and local stoichiometry.

Thermal properties of SbxSe100−x glasses studied by modulated temperature differential scanning calorimetry

We report on three-dimensional optical data storage inside a silica glass by using a focused 800 nm, 120 fs, 200 kHz pulsed laser. The glass is transparent in the wavelengths ranging from 250 to 1000 nm. After the irradiation of the 800 nm tightly focused femtosecond laser, a refractive-index bit was formed in the glass. The relations between the size of refractive-index bit versus average power and irradiation duration of the laser pulse have been examined. Absorption and ESR spectra showed a significant increase in the concentration of SiE′ color centers in the laser irradiated glass. A multi-photon absorption process is considered to have occurred in the glasses when irradiated by the laser pulses. We suggest that writing three-dimensional refractive-index bit inside the transparent glasses based on a multi-photon absorption process will become a promising method to fabricate optical memory with both an ultrahigh storage density and an ultrahigh recording speed.

Three-dimensional optical storage inside a silica glass by using a focused femtosecond pulsed laser

Thin films of different thicknesses in the range 400–1600 A have been vacuum deposited on clean glass substrates held at room temperature by very fast evaporation of the Se10Sb10Te80 bulk alloy. The thermoelectric power of these films has been measured as a function of temperature during heating and cooling cycles by the integral method. It is found that the thermoelectric power of these films is slightly different during the heating and the cooling cycles which is ascribed to slight reorientation of microcrystallites as also evidenced by x‐ray diffraction. It is further found that the thermoelectric power (at a constant temperature) is a function of film thickness; it varies nearly linearly with reciprocal thickness. From these data, the nature of carrier scattering in the films has been ascertained. From the energy‐dispersive x‐ray analysis patterns of the films the semiquantitative content of the constituent elements Sb, Se, and Te has been determined.

Thermoelectric power of ternary semiconductor Se10Sb10Te80 thin films

Thin Films of thicknesses less than 1000 A have been deposited in a vacuum of 5 ×10-5 Torr by the very fast evaporation (~50 A/s) of the ternary Se10Sb10Te80 bulk alloy pieces onto cleaned glass plates which were held at room temperature vertically above the evaporation source (at a distance of 25 cm) From the energy dispersive X-ray analysis (EDAX) patterns of the films, the presence of Te, Sb and Se has been confirmed and the semi-quantitative content of the constituent elements in the alloy films has been determined Film specimens for transmission electron microscopy have been detached from these glass substrates by dippping the latter in very dilute HF solution These film specimens have been examined in an electron microscope Electron diffraction patterns reveal that the films are not amorphous but are polycrystalline in most of the regions, but also single crystalline in some regions which have a darker contrast in bright field transmission electron micrographs Analysis of the single crystalline (spot) patterns obtained reveals that the single crystalline microcrystallites in different regions are oriented differently The orientations of these microcrystallites have been determined

Electron Microscopic Studies and Microchemical Analysis of Se 10Sb 10Te 80 Ternary Alloy Thin Films

Different thickness thin films of the ternary alloy Ga5Se20Te75 have been vacuum deposited on clean glass substrates held at room temperature at a very fast rate. The film resistance has been measured as a function of temperature during two cycles of heating and cooling. It has been found that the resistance‐temperature (R‐T) variation of the films during first heating and cooling is different, the R‐T curve during heating lying above the R‐T curve during cooling in the case of thinner films and below in the case of thicker films. There are two possible explanations for the difference in resistance variation during heating and cooling and between the thinner and thicker films. The first is due to the semiconducting nature of the material and the second is due to the removal of frozen‐in defects and/or change in concentration depth profile. In addition to these, the phenomenon of self‐annealing can also take place in thicker films. Log resistance vs reciprocal temperature plots are found to be linear, indi...

K. S. Raju

Papers

Thermoelectric power of ternary semiconductor Se10Sb10Te80 thin films

Electron Microscopic Studies and Microchemical Analysis of Se 10Sb 10Te 80 Ternary Alloy Thin Films

Electrical conduction in ternary semiconductor Ga5Se20Te75 thin films