Intermixing and lateral composition modulation in GaAs/GaSb short period superlattices

Lateral composition modulation on the group V sublattice has been investigated in GaAs/GaSb short period superlattices. The effect of As species and growth temperature on the appearance of lateral composition modulation was studied. Cross-sectional transmission electron microscopy and x-ray diffraction reciprocal space maps reveal that structures grown using As tetramers are always disordered, defective, and phase separated. Also, in these structures the As-rich regions appear to be composed of stacked GaAs quantum dots embedded in a GaSb matrix. The structures grown with As dimers show improved crystalline quality. Short period superlattices grown at T<420 °CT<420 °C have flat interfaces and are laterally homogeneous, however, there is significant anion intermixing across the interfaces. Structures deposited at 420 °C<T<445 °C420 °C<T