Valence Band Structure of Si–As–Te Chalcogenide Glasses Prepared in the Gravity Environment of the Earth and in a Microgravity Environment in Space

Photoemission spectra have been measured for two kinds of Si 9 As 14 Te 21 chalcogenide glasses, prepared in the gravity environment of the earth and in a microgravity environment in space, respectively. The valence band structures of both of the glasses are in general similar, but exhibit a distinct difference close to the Fermi level. The top of the valence band states splits into a non-bonding level and a bonding level. The bonding/non-bonding splitting is smaller for space-made material than for its terrestrial-made counterpart. The X-ray Photoelectron Spectra indicate that the top of the valence band has a non-bonding lone-pair characteristic in the case of terrestrial-made material and a covalent bonding characteristic in the case of space-made material.