Study of Structural and Optical Properties of Non-Oxide Se90Cd10–xSbx(2 ≤ x ≤ 8) Chalcogenide Thin Films

Thin films of Se90Cd10–xSbx (2 ≤ x ≤ 8) of thickness 0.4 microns were prepared on ultra-clean glass substrate by thermal evaporation technique. The vacuum level was 10–6 torr. This paper intends to investigate the impact of Sb concentration on the optical characterization. XRD measurement has been done to investigate the Structural characterization of the prepared thin films. XRD result indicates the prepared thin have amorphous nature. To analyze the optical characterization of the thin films the absorption spectra were recorded over 400–1100 nm wavelength range. In the present study the optical absorption follows direct allowed transition. An increase in photon energy causes an increase in absorption coefficient while extinction coefficient has been found to increase with an increase in frequency of the photons i.e., deceases with increase of wavelength. Optical bandgap (Eg) of thin films have been studied and an increase in it has been recorded with increasing Sb concentration.

Optical Investigations of In2Se2.7Sb0.3 Thin Films Prepared by Thermal Evaporation Technique

The III-VI compound semiconductors are important for the fabrication of ionizing radiation detectors, solid-state electrodes, and photosensitive heterostructures, solar cell as well as ionic batteries. In this paper, In2Se2.7Sb0.3 thin films have been grown by thermal evaporation technique onto a with chemically clean glass substrate. Amorphous nature of the films has been discovered by UV-VIS spectrophotometer. The analysis by absorption spectra within the spectral range 200nm -900 nm has been used for the optical characterization of thin films. From these data the optical constants (absorption coefficient (α), refractive index (η), extinction coefficient (k)) and optical band gap (Eg) are studied. The results were discussed, and reported in detail.

The effect of thickness on the optical properties of Cu2S thin films

In this work, the optical properties of Cu2S with different thickness(1400, 2400, 4400) Ǻ have been prepared by chemical spray pyrolysis method onto clean glass substrate heated at 283 oC ±2. The effectof thickness on the optical properties of Cu2S has been studied. Itwas found that the optical properties of the electronic transitions onfundamental absorption edge were direct allowed and the value of theoptical energy gap of Cu2S (Eg) for direct transition decreased from(2.4-2.1) eV with increasing of the thickness from (1400 - 4400)Ǻrespectively. Also it was found that the absorption coefficient isincreased with increasing of thicknesses. The optical constants suchas extinction coefficient, refractive index and the imaginary part ofthe dielectric constant have similar termed of variation for theabsorption coefficient.

Synthesis and characterization of screen-printed CdS films

Cadmium sulphide films having energy band gap of 2.4 eV found applications in solar cells and electroluminescent devices. CdS polycrystalline films have been prepared on ultra-clean glass substrate by screen-printing technique and then sintered in air. Optimum conditions for preparing good quality screen-printed films have been found. The optical band gaps ?Eg? of the CdS films were determined from the UV transmission spectroscopy and were found to be 2.47eV. The Wurtzite structure of CdS films was confirmed by X-ray diffraction analysis. DC conductivity and activation energy of films was also measured in vacuum by two-probe technique.

STRETCHING OF SINGLE DNA MOLECULES BY LANGMUIR–BLODGETT METHOD

We propose a new method that double-stranded DNA molecules can be stretched and immobilized on the clean glass substrate by using a lipid monolayer at the air–water interface. This method is based on the substrate lifting of Langmuir–Blodgett method. We observed fluorescence images of polyion complex films with a scanning near-field optical microscope (SNOM). As a result, straight fluorescent lines aligned parallel to the lifting direction were observed and it was considered that isolated single DNA molecules were extended to align on the substrate. This method is applied to various DNA molecules.