Photoluminescence of monolayer to submonolayer thick Ge_(1-x)C_z on si(001)

摘要

A detailed photoluminescence (PL) study elucidates the epitaxial limits for nominally pure and optically active Ge_(1-z)C_z layers on Si(001) substrates. The C content is varied from z = 6/100 to z = 100/100 and the layer thicknesses are changed from 0.05 monolayers (ML) to 3 ML. With increasing C fraction the thickness for which the PL signal can be detected gradually decreases. Excitation dependent PL experiments reveal a type I band edge alignment for z ≥ 29/100 and a type II alignment for z ≤ 12/100.