Publication Type
Journal
Journal Name
Journal of Applied Physics
Publication Date
Volume
701
Issue
1
Abstract
The optical dielectric function of bismuth germanate Bi4Ge3O12 has been measured using
spectroscopic ellipsometry and optical transmission. Analysis near the direct band edge indicates
that there are at least three critical points at 4.44 low intensity and at 4.75 and 4.91 high intensity.
Using transmission measurements, the band gap is determined to be 4.20 eV, which is likely
determined by the defects in the material. Comparisons are made with relativistic electronic
structure and optical calculations based on the Engel–Vosko generalized gradient approximation.
The near-absorption-edge critical points are associated with spin-orbit-split bands which
significantly modify the conduction bands.
