NONLINEAR LASER-INDUCED REGIME OF SURFACE-ELECTROMAGNETIC-WAVE GENERATION AND SUBMICRON PERIODIC RELIEF DURING LIQUID-PHASE PHOTOCHEMICAL ETCHING OF N-III-V SEMICONDUCTORS

This paper is devoted to an experimental study of the physical process es underlying the phenomenon of laser-induced generation of periodic r elief on the surface of n-III-V semiconductors during liquid-phase pho tochemical or photoelectrochemical etching accompanying the resonance interaction of surface electromagnetic waves (SEWs). The increments of the exponentially increasing amplitudes of the dominant Fourier harmo nics of the relief have been measured at the initial (linear) stage of the time evolution of the surface profile. It is proven by comparing the theoretical and experimental results that the mechanism for formin g periodic structures that we have proposed is adequate. Ways of monoc hromatizing the generated relief and controlling the line shape of the surface grating are studied. It is experimentally detected for the fi rst time that the nonlinear stage of the time evolution of the relief is characterized, in accordance with the predictions of the theory dev eloped by the authors, by amplitude and phase oscillations of the firs t and second Fourier harmonics of the surface profile. It is shown to be possible to generate relief that suppresses specular reflection fro m the surface. A new nonmasked laser method is developed for forming h igh-quality submicron relief diffraction gratings, combining a hologra phic method and a method involving laser-induced relief generation dur ing resonance excitation of SEWs. Diffraction gratings with a period o f d=0.24-0.54 mu m and a depth of h=0.1-0.2 mu m over an area of 0.5x1 cm have been created on an n-InP surface. (C) 1997 American Institute of Physics.