Excitons in Indirect Electroabsorption

Abstract
Exciton effects have been included in a calculation of the indirect differential electro-absorption coefficient at the fundamental optical absorption edge of Ge. The theory is in very good agreement with experiment; this is the first successful attempt to obtain a quantitative fit to electroabsorption data. The theoretical fit yields a value of 0.6701 eV for the indirect band gap of Ge at 296°K.