Enhanced carrier diffusion lengths and photon transport in AlxGa1−x As/GaAs structures

Several novel features are observed in the low-temperature photoluminescence spectra of AlxGa1−xAs layers grown on GaAs by metalorganic chemical vapor deposition. GaAs substrate luminescence spectra are observed through AlxGa1−xAs layers as thick as 22 μm. Both carrier diffusion to the substrate and AlxGa1−xAs luminescence are identified as the excitation mechanisms of the GaAs luminescence, and a minority-carrier diffusion length of 10 μm is estimated. The presence of photon recycling in the AlxGa1−xAs layers is demonstrated by comparison of photoluminescence (PL) spectra for layers with and without GaAs substrates, as well as PL examination of two AlxGa1−xAs heterostructures.