A. K. Agnihotri

The X-ray K-absorption studies in glassy Se80Te20 and Se80Te10Sb10

Abstract X-ray K-absorption studies have been made in glassy Se 80 Te 20 and Se 80 Te 10 Sb 10 alloys and their amorphous films. It has been observed that the Se K-edge shifts towards the lower energy side in both alloys, shifting more in ternary alloy than in binary alloy. Our results are in agreement with the published work on infra-red and Raman spectroscopies.

X-ray spectroscopic studies of the glassy GexSe100−x system

Abstract X-ray K-absorption edges of germanium and selenium have been studied in glassy GexSe100−x (x=10, 15, 22 and 30). We find that the Ge K-absorption edge always shifts towards higher energies with respect to pure amorphous germanium whereas the Se K-absorption edge always shifts towards lower energies with respect to amorphous selenium. In both cases, the shift is found to be a minimum for the particular value x=22 which indicates some modifications in the structure at this composition.

Structural studies in Ge22Se68X10 (X=Bi, Sb) glasses and their amorphous films by X-ray spectroscopy

The X-ray K-absorption edges of Ge and Se in glassy Ge 22 Se 78 and Ge 22 Se 68 X 10 ( X = Bi, Sb) have been studied in bulk as well as in thin films. We find that the Ge K-edge shifts in bismuth-doped glassy alloy while the Se K-edge remains unchanged. However, in Sb-doped glassy alloy the Ge K-edge remains unchanged while the Se K-edge shifts towards the lower energy side. These results indicate that Bi-Ge bonding is favoured in Ge-Se-Bi and Se-Sb bonding in Ge-Se-Sb alloys.

The X-ray K absorption edges of Ge and Se in Ge22Se78−x Bi x glasses and amorphous films

Abstract The X-ray K absorption edges of Ge and Se in glassy Ge22Se78−x Bi x with x =0, 2 and 10 have been studied in bulk as well as in thin-film form. In both cases, we find that, at a low concentration of Bi (x =2), the Se K edge shifts while that of Ge remains unchanged. On the other hand, at a higher concentration of Bi (x = 10), the reverse happens. The results indicate different kinds of bonding at low and high concentrations of Bi. The results are in agreement with those of other workers who drew similar conclusions from the electrical properties.

Photocrystallization in amorphous thin films of Se100-xInx

Abstract The present paper reports a systematic study of photocrystallization in a-Se100−xTex films (0 ⩽ x ⩽ 25). The photocrystallization is achieved by shining white light at room temperature for different exposure times. The results indicate that photocrystallization is highly composition dependent in a-Se100−xTex system.

Composition dependence of photoconductivity in a-Se100−xTex

Abstract The present paper reports the composition dependence of dark and photoconductivities in vacuum evaporated thin films of Se100−xTex where x is varied from 5 to 30. It is observed that the dark conductivity (σd) increases monotonically with T concentration while the photoconductivity (σph) saturates at higher concentrations of Te (x > 15) · σ ph σ d shows a maximum and the pre-exponential factor (σ0) a minimum at 15 at% of Te which indicates some structural changes at higher concentration of Te as also reported in other measurements.

X-ray K-absorption studies of glassy Ge22Se68M10 (M=Ag, Cd, In, Pb)

Abstract X-ray K-absorption studies of glassy Ge22Se78 and Ge22Se68M10 (M = Ag, Cd, In, Pb) have been made in order to understand the nature of bonding of metallic atoms in ternary alloys. The edge shift is found to be dependent on the difference in electronegativity between the metallic atoms and the Ge or Se atoms. The results are in agreement with Paulings concept of electronegativity and indicate that the nature of the bonds in these glasses is iono-covalent in character as found in many crystalline solids.

Composition dependence of photoconductivity in amorphous thin films of Se80−xTe20Inx

The present paper reports the composition dependence of steady-state and transient photoconductivity in amorphous thin films of Se70Te30-xSbx, wherex is varied from 0 to 10. The results indicate that photoconductivity is highly composition dependent in this system and a discontinuity in various electrical parameters is observed at 4 at. % of Sb. This is explained in terms of increased disorder up to 4 at. % of Sb. However, at higher concentration of Sb, an ordered structure may be established due to the formation of microcrystalline phases as observed in X-ray diffraction patterns.

X-ray spectroscopic studies of photo-structural changes in glassy Se100-xTex

Recently it has been reported that reversible and irreversible photo-structural changes occur in amorphous chalcogenide glasses. The present paper reports an X-ray spectroscopic study of Se100-xTex (x=5 to 30) alloys before and after the light exposure. The results indicate that no change in Se K-edge occurs upto x=5 at%. However, at higher concentration of Te (x>5 at%), Se K-edge shifts towards higher energy side with respect to Se K-edge in unexposed sample. A high energy shift of the K-absorption edge of Se in the present case may, therefore, be related to photocrystallization due to light exposure. The results also indicate that the photocrystallization is highly composition dependent in Se100-xTex glassy system.

Photocrystallization in amorphous thin films of Se80−x Te20In x

Investigation of the effect of In as a third element on photocrystallization in the Se-Te-In system. Photocrystallization was achieved by shining white light (3000lx) for different exposure times. Glassy alloys of a Se 8 0 -x Te 20 In x (x=0,5,15 and 20) were prepared by the quenching technique. Thin films of these alloys were prepared by vacuum evaporation, keeping substrates at room temperature at a base pressure of about 1.3mPa