Optical second harmonic imaging: a versatile tool to investigate semiconductor surfaces and interfacesT. Scheidt, E. G. Rohwer, H. M. von Bergmann and H. StafastEur. Phys. J. Appl. Phys., 27 1-3 (2004) 393-397DOI: https://doi.org/10.1051/epjap:2004069