Low-Temperature Growth of AlAs/GaAs Heterostructures by Modulated Molecular Beam Epitaxy

Modulated molecular beams phase-locked to reflection high-energy electron diffraction (RHEED) oscillations have been used to grow low-temperature GaAs quantum wells (QW) confined by AlAs/GaAs short-period superlattices (SL). Two different phase-locked modulation growth modes were attempted and compared. In the first mode, only the As4 beam was interrupted periodically in-phase with the monolayer growth cycle. In the second one, both Ga (or Al) and As4 incident beams were modulated synchronously with the monolayer period. Both growth methods were seen to produce high-optical-quality QW and SL's layers at low-growth temperatures (T s≃400°C).