X-ray spectroscopic investigation of bismuth selenide, bismuth telluride and their alloy

Abstract

The Bi L_III and SeK-absorption discontinuities in Bi₂Te₃, Bi₂Se₃and Bi₂Te₂Se have been studied using a 40 cm dia. bent crystal x-ray spectrograph. The Bi edge in these compounds is found to shift to higher energies with respect to that of the metal. The Se edge on the other hand moves to lower energy in Bi₂Se₃ and to higher energy in Bi₂Te₂Se. The x-ray absorption data on Bi₂Se₃ and Bi₂Te₂Se brings out clearly the difference in the nature of the chemical bond two types of selenium atoms. Se₁ and Se_II, have in these compounds. An alternative bonding picture is proposed for Bi₂Se₃ to remove deficiencies in drabble and goodman's scheme.