Strain-compensated GaPN/GaP heterostructure on (0 0 1) silicon substrates for intermediate band solar cells

Abstract

In this study, we investigate strain-compensated GaPN/GaP heterostructure on silicon substrates for intermediate band solar cells (IBSCs) grown by metalorganic vapour phase epitaxy. GaPN is an interesting material as it may be used to compensate the residual strain created by the lattice mismatch between silicon and GaP. Strain compensation in GaPN/GaP heterostructures is studied by Raman scattering through the investigation of strain-induced frequency shift of the LOΓ phonons. The electronic states of GaPN are examined by Raman scattering, photoreflectance (PR) measurements and band-anticrossing (BAC) model calculations. Raman scattering measured at 1.959 and 2.331 eV shows a resonant behaviour with E− energy states at Γ-point and the Nx level locating close to X-point, respectively. Raman scattering results are correlating with PR measurements and BAC model. Raman scattering and PR measurements are providing clues of a conduction-band splitting which may enable the fabrication of IBSCs on silicon substrates.