Energy Up-Conversion at GaAs-GaInP2 and GaAs-AlGaInP2 Interfaces Caused by Cold Auger Processes

Efficient, low-temperature luminescence at energies far above that of the exciting cw-laser is reported at junctions of GaAs-GaInP2 and GaAs-AlxGa1-xInP2. The signal originates from the high-band gap layers and disappears only if the excitation energy is tuned below the GaAs band gap, as monitored by up-converted photoluminescence excitation spectroscopy. This shows that the non-linear process isinduced by the generation of electrons and holes in the GaAs. Furthermore, it is found that the up-conversion is only observed if the (Al)GaInP2 layers are CuPtB long-range ordered. The reason for this is the inherent presence of metastable states in these ordered alloys. It is argued that cold Auger processes cause the non-linear effect at these type I interfaces.