Pulsed laser crystallization of SiGe alloys on GaAs

SixGe1−x films and heterojunctions produced by epitaxial crystallization of a-SixGe1−x alloys on GaAs

“…Four structures are observed in the first-order Raman signal: the LO-phonon from the GaAs substrate (LO-GaAs, at 292 cm À1 ) as well as the Ge-Ge ($300 cm À1 ), Si-Ge (around 400 cm À1 ) and Si-Si ($500 cm À1 ) modes from the LC Si 1Àx Ge x layers. The well-defined Si-Ge peaks in the crystallized a-Ge/a-Si multilayers show that the Si and Ge layers completely intermix during LC leading to a homogeneous Si 1Àx Ge x (the latter was also confirmed by secondary ion mass spectrometry, SIMS [6]). The composition x estimated from the position of the Si-Si peak, which displays a large (up to 60 cm À1 ) and monotonic energy shift as x increases from 0 to 1, agrees well with the values reported in Ref.…”

“…As demonstrated in Ref. [6], the layers completely mix during LC, leading to the formation of a homogeneous crystalline (c-) Si x Ge 1Àx alloy.…”