Study of GaAsSb:N bulk layers grown by liquid phase epitaxy for solar cells applications

We present an original study of bulk epitaxial GaAsSb:N layers in view of photovoltaic applications of this material. The layers are grown on n-GaAs substrates by low-temperature liquid phase epitaxy (LPE). The grown GaAsSb: N layers exhibit reproducible properties and good optical quality. A number of experimental methods including x-ray diffraction, energy dispersive x-ray spectroscopy, atomic force microscopy, x-ray photoelectron spectroscopy and Raman spectroscopy are applied for investigation of the structural properties, surface morphology, local arrangement and chemical bonding of Sb and N in the obtained compounds. The band gap values at room temperature assessed from surface photovoltage and photoluminescence (PL) measurements are in good agreement and are similar to 20 meV lower than those of reference GaAsSb layers. PL spectra measured at different temperatures (10-300 K) show a very weak S-shape-like behaviour of the PL peak energy position indicating minimal carrier localization. The obtained results reveal the capacity of the LPE for growing bulk GaAsSb: N layers with good optical quality.