Below‐band‐gap photon recycling in AlxGa1−xAs

A long minority‐carrier diffusion length and the transmission of Alx Ga1−x As luminescence through Alx Ga1−x As layers are identified as two processes causing the excitation of GaAs spectra through thick Alx Ga1−x As layers, as well as contributing to enhancements in low‐temperature photoluminescence intensity observed in Alx Ga1−x As layers without GaAs substrates. A simple model for intensity enhancement due to below‐band‐gap photon recycling is introduced to explain the observed enhancements. Some features that uniquely distinguish below‐band‐gap photon recycling from the better known room‐temperature process are presented.