Interaction of Polyatomic Bi Ions with Ge and Si


Interaction of Polyatomic Bi Ions with Ge and Si

Liedke, B.; Böttger, R.; Heinig, K.-H.; Bischoff, L.; Hübner, R.; Pilz, W.

Si and Ge surfaces were irradiated with polyatomic Bi ions at normal incidence with energies between 10 and 20 keV per atom. For comparison, irradiation with monatomic ions was performed. The resulting surface morphologies were studied by SEM, XTEM and AFM. A variety of surface patterns were revealed, which are based on different formation mechanisms. Irradiation of Ge with Bi3 , Bi3 and Bi2 at RT results in a surface morphology of hexagonally ordered dots. They have an aspect ratio close to one, which has not been reported for elemental semiconductors so far [1]. For comparison, Ge irradiated with monatomic Bi ions at RT leads to well-known sponge-like surface layers, whereas with increasing substrate temperature similar dot patterns appear [2]. On Si irradiated at RT with monatomic or polyatomic Bi ions, no dot patterns have been found, which holds for Bi even for T>RT. On Si dot patterns appear only after polyatomic Bi irradiation well above RT.
The surface patterns will be explained by models based on vacancy kinetics and the liquid-solid phase transition. The sponge formation, as suggested in literature, results from vacancy kinetics, and will be demonstrated by kinetic Monte-Carlo simulations. The dot patterns are consistently modeled by ion-induced transient local melt pools, using TRIM simulations and heat conduction calculations.

Keywords: FIB; polyatomic irradiation; KMC; TRIM; Bi ions; Ge; Si; surface patterning

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Publ.-Id: 18558