National Research Council of Canada. NRC Institute for Microstructural Sciences
High resolution X-ray diffraction; Transmission electron microscopy; Secondary ion mass spectrometry; Molecular beam epitaxy; GaInNAsSb; InGaNAsSb
GaInNAs(Sb)/GaNAs double quantum well (DQW) structures were grown on GaAs substrates using solid-source molecular beam epitaxy with N2/Ar gas mixtures in a radio frequency plasma cell. A novel method of in situ antimony mass spectrometry is introduced which permits flux monitoring in the presence of large arsenic background pressures. For a DQW sample grown without Sb, bright and narrow (38.1 meV) room temperature photoluminescence (PL) emission at 1509nm was achieved after optimized rapid thermal annealing. In two samples grown with antimony fluxes of approximately 0.012 and 0.028 monolayers/s the PL intensity improved and very bright PL was observed at 1518 and 1551nm with linewidths of 33.1 and 35.0 meV, respectively. The integrated PL intensities of each of these two samples was equivalent to the emission for a reference GaInNAs/GaAs DQW sample emitting closer to 1:3 mm. More strikingly, the intensity of the Sb-free 1509nm sample was only lower by a factor of 2. This suggests that the N2/Ar plasma approach has benefits for the material quality, as well as providing efficient flux control, yielding good material even without Sb. High-resolution X-ray diffraction and transmission electron microscopy measurements indicate excellent crystal quality for all samples. Secondary ion mass spectrometry reveals a dramatic tendency for Sb segregation during growth, resulting in very asymmetric incorporation with most of the Sb atoms located at the top interface.