Wavelike Periodic Structures on the Silicon Surface Initiated by Irradiation with a Focused Gallium Ion Beam

We investigate the processes of microrelief formation on a Si(100) surface under irradiation with a Ga+-ion beam with an energy of 30 keV and a fluence of D = 1.25 x 10(18)-2 x 10(19) cm(-2) at incident angles of theta = 30 degrees-85 degrees. Within the angular range of theta = 40 degrees-70 degrees, a faceted wavy relief forms on the Si surface, while at theta = 30 degrees, a sinusoidal relief develops. An experimental dependence of the periodic structure wavelength as a function of irradiation time lambda(t) similar to t (n), where n = 0.33-0.35, is obtained. The average values of relief propagation velocities and their direction relative to the incident ion direction are determined for theta = 30 degrees and 40 degrees, amounting to -5.3 +/- 0.6 and -6.3 +/- 0.6 nm s(-1), respectively. The results are discussed in detail within the framework of existing models of wavelike surface relief formation under ion bombardment.