OSCILLATORY EVOLUTION OF AN ION-BOMBARDED INSB(100) SURFACE

Low energy ion-scattering and ion-recoil (LEIS and LEIR) spectroscopies have been used to monitor the structure and composition of an InSb (100) surface during continuous irradiation with argon ions (4.8 keV) directed at grazing incidence. Oscillations in both the scattered and recoil ion intensities have been observed during all bombardment sequences (for doses > 2 x 10(16) ions/cm2). The periods of these oscillations show some dependence on the experimental geometry, and are close to those predicted for sputter-removal of one or two surface layers. Interestingly, the surface shows no sign of becoming amorphous even following excess ion bombardment. Details of the variations in surface composition are assigned, not only to layer-by-layer depth profiling, but also by rapid diffusion of Sb to the surface from the Sb depleted lattice. These data indicate that LEIS and LEIR can be used to monitor composition profiles with monolayer depth resolution such that different states of the same surface can be achieved simply and controllably by terminating ion bombardment following a pre-determined irradiation dose