Abstract
Simultaneous molecular beam epitaxial growth of GaAs/AlGaAs multiple quantum wells on two different substrates (one on GaAs (100) and another on a GaAs substrate misoriented by 4° in the (111) direction) resulted in samples of similar structure, but having different defect profiles. The on-axis sample had a higher defect density and more types of electron traps than the off-axis counterpart. Temperature-dependent terahertz (THz) emission and temperature-dependent photoluminescence were measured; in both cases, an intensity quenching was observed between 75 K – 250 K for the on-axis sample, but not in the off-axis sample. We attribute the THz emission quenching to the electron traps present in the sample, which decreases the photocarriers participating in setting up the surface field.
Highlights
Defects in bulk semiconductors and heterostructures can have considerable influence on different applications and corresponding operating temperatures
Results from the high resolution X-ray diffraction (XRD) rocking curves, showing only AlGaAs satellite peaks, are presented in Fig.[3]
The PL peak positions indicate that the difference in periodicity observed in the XRD diffraction should likely be accounted for by difference in AlGaAs barrier thickness and not due to the GaAs well thickness
Summary
Defects in bulk semiconductors and heterostructures can have considerable influence on different applications and corresponding operating temperatures. Intentionally increasing defects through low-temperature growth or post-growth treatments (where AsGa defect concentrations are at ∼1020 cm-3 after growth and ∼1017 - 1018 cm-3 after post-growth annealing9), are often done on GaAs in preparation for faster applications such as photoconductive antennas or switches.[10,11]
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