Role Of Nitrogen In Photoliminescence Up-Conversion In Gainnp/Gaas Heterostructures

Alloying of disordered GaInP with nitrogen is shown to lead to very efficient PLU in GaInNP/GaAs heterostructures grown by gas source molecular beam epitaxy (GS-MBE). This is attributed to the N-induced changes in the band alignment at the GaInNP/GaAs heterointerface from the type I for the N-free structure to the type II in the samples with N compositions exceeding 0.5%. Based on the performed excitation power dependent measurements, a possible mechanism for the energy upconversion is suggested as being due to the two-step two-photon absorption. The photon recycling effect is shown to be important for the structures with N=1%, from time-resolved PL measurements.