We present an experimental and theoretical study of GaInAs(Sb)N layers with
thickness around 2 μm, grown by liquid-phase epitaxy (LPE) on n-type GaAs substrates. The
samples are studied by surface photovoltage (SPV) spectroscopy and by photoluminescence
spectroscopy. A theoretical model for the band structure of Sb-containing dilute nitrides is
developed within the semi-empirical tight-binding approach in the sp3
d
5
s*sN parameterisation
and is used to calculate the electronic structure for different alloy compositions. The SPV
spectra measured at room temperature clearly show a red shift of the absorption edge with
respect to the absorption of the GaAs substrate. The shifts are in agreement with theoretical
calculations results obtained for In, Sb and N concentrations corresponding to the
experimentally determined ones. Photoluminescence measurements performed at 300K and 2 K
show a smaller red shift of the emission energy with respect to GaAs as compared to the SPV
results. The differences are explained by a tail of slow defect states below the conduction band
edge, which are probed by SPV, but are less active in the PL experiment.