Surface photovoltage and photoluminescence study of thick Ga(In)AsN layers grown by liquid-phase epitaxy

Abstract

We present an experimental and theoretical study of Ga(In)AsN layers with a thickness of around 1 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. Theoretical calculations of the electronic structure and the spectral dependence of the dielectric function are carried out for different nitrogen concentrations using a full-band tight-binding approach in the sp3d5s*sN parameterisation. 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. This shift, combined with the results of the theoretical calculations, allows assessing the nitrogen concentration in different samples. The latter increases with increasing the In content. The analysis of the SPV phase spectra provides information about the alignment of the energy bands across the structures. The photoluminescence measurements performed at 2 K show a red shift of the emission energy with respect to GaAs, in agreement with the SPV results.