Bulk dipolar contribution to second-harmonic generation in zincblende

Abstract

We present a comprehensive analysis of second-harmonic generation (SHG) in a diatomic zincblende crystal based on the simplified bond hyperpolarizability model (SBHM) and compare the result with two rotational anisotropy (RA)SHG experiments on a nonvicinal zincblende lattice. We show that bulk dipolar sources alone are sufficient to describe the experimental data by implementing the SBHM previously applied for silicon surfaces to bulk lattices containing two different atoms, e.g., Ga and As. It is shown that a second-rank tensor for a Td point group has only one independent component and this tensor is equivalent to the one derived by the SBHM model using an effective bulk hyperpolarizability αGaAs=(αGa−αAs). In addition, SBHM gives an excellent fit with the RA-SHG experiments of GaAs using a single fitting parameter if Fresnel transmission factors are also incorporated in the model, suggesting strongly that bulk dipolar contribution is the dominant SHG source in a zincblende lattice.