Second-harmonic generation and nonlinear reflection on the surfaces of class m3m semiconductor crystals

A theory of second-harmonic generation and nonlinear electroreflection on the surfaces of class m3m semiconductor crystals is developed taking account of the absorption of the pump and second-harmonic waves. The nonlinear polarisation is represented by a sum of three contributions: quadrupole bulk, dipole surface, and dipole associated with disturbance of the inversion in the surface layer by an electrostatic field. Expressions for these contributions are derived for the (001), (110), and (111) faces and also, in the approximation of small angles of refraction, for the dependences of the intensities of the p- and s-polarised waves of the reflected second harmonic on the surface potential and on the angle of tilt of the reflecting surface relative to its normal. An analysis is made of the suitability of the method of generation of a reflected second harmonic for the diagnostics of semiconductor crystal surfaces.