Gas-Source Molecular Beam Epitaxy Growth and Characterization of GaNP/GaP Structures

ABSTRACTGaNP bulk layers with different N concentrations and GaN0.025P0.975/GaP multiple quantum wells (MQWs) with various well thicknesses were grown on (100) GaP substrates by gas-source molecular beam epitaxy with a RF nitrogen radical beam source. Using high-resolution X-ray rocking curves, photoluminescence (PL) and absorption measurements, we have shown that incorporation of N in GaNxP1−x, alloys (x ≥0.43%) leads to a direct bandgap behavior of GaNP, and yields strong room-temperature PL from the epilayers. A large Stokes shift of 200 meV is found between the PL peak energy and the absorption edge for the GaNP epilayers, indicating a very strong carrier localization. From the PL peaks of a series of GaN0.025P0.975/GaP MQWs with different well thicknesses grown at the same growth condition, a large conduction-band effective mass mc* − 0.9 me has been obtained for the GaN0.025P0.975alloy, indicating a mixing of Γ and X band wave functions in the conduction band