Rigorous analysis of photoluminescence efficiency for characterisation of electronic properties of InP(1 0 0) surfaces

A rigorous theoretical analysis of the band-edge photoluminescence efficiency (Y_PL) versus excitation intensity (Φ) and surface Fermi level (E_F0) was performed for n-type InP(1 0 0) surfaces. A strong influence of the surface state density (N_SS) and band bending (field-effect passivation) on the Y_PL(Φ) spectra was found. Furthermore, the electronic parameters of the chemically polished InP(1 0 0) surface, including the U-shaped distribution of surface states N_SS(E) and their cross sections for capturing electrons (σ_n) and holes (σ_p) were determined. In this order, we compared the simulated Y_PL(Φ) dependencies to the experimental data taken from the literature using the fully computer fitting procedure based on Genetic Algorithm. We reproduced very well the experimental Y_PL(Φ) dependence which exhibited a strong increase of Y_PL and attributed this effect to a gradual saturation of surface states. We also found that the surface non-radiative recombination of electron-hole pairs dominates the bulk recombination channels (in terms of recombination rates) and governs the behaviour of radiative recombination versus Φ. In addition, we analysed the evolution of the surface quasi-Fermi levels for electrons (E_Fn) and holes (E_Fp) as a function of photo-excitation intensity.