Antimony enhanced homogeneous nitrogen incorporation into GaInNAs films grown by atomic hydrogen-assisted molecular beam epitaxy

In this work, we investigated the effect of Sb on N-induced localized states in GaInNAs films. From 77 K photoluminescence (PL) spectra for GaInNAs(Sb) films grown with different Sb fluxes, single band-to-band emissions observed in all samples. The emission wavelength redshifts with increasing Sb flux, which corresponds to an increase in Sb composition. The PL intensity and full-width at half maximum (FWHM) are both improved for a narrow range of Sb flux of 1 - 5 × 10^-8 Torr. On the other, higher Sb flux deteriorates the PL characteristics. It can be thought that any higher Sb flux induces some kind of Sb-related defects such as SbGa antisites. Further in temperature dependent PL measurements, energy shifts, so-called “S-shaped” curves, were observed in all samples, which indicate a strong carrier localization. Although GaInNAs sample showed a large energy shift of 53 meV, irradiation of Sb decreases the localization energies to 13-22 meV. These results show that Sb can enhance the homogeneity of GaInNAs alloy, since the carrier localization is led by inhomogeneous N incorporation. The internal quantum efficiency characteristics for GaInNAsSb solar cell also improved by introducing an optimum amount of Sb and a redshift of fundamental absorption edge into 1 eV range was achieved.