Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Irradiation of solids by heavy polyatomic ions (e.g. Aunm+ or Binm+) can cause localized melting at the ion impact point due to the enhanced energy density in the collision cascade of a polyatomic heavy ion impact [1,2]. Former studies demonstrated the formation of high aspect ratio, hexagonal dot patterns on Ge, Si or GaAs after high fluence, normal incidence irradiation using a mass separated FIB system choosing a suited combination of energy density deposition (i.e. poly- or monatomic ions) and substrate temperature, which facilitated transient melting of the ion collision cascade volume [2-5].
This study underscores the universality of this ion impact-melting-induced, self-organized pattern formation mechanism probing the compound semiconductor GaSb under polyatomic Aunm+ ion irradiation with various irradiation conditions in particular, ion species, fluence, energy/atom, temperature and angle of incidence.
Calculations of the needed melting energies per atom (Emelt) for different materials show, that among others GaSb is a preferring candidate for a successful surface patterning by mon- and polyatomic heavy ions whereas i.e. the surface of SiC remains stable under the given conditions.
HRSEM, AFM and EDX analysis of irradiated surfaces reveal that for compound semiconductors, additional superstructures are evolving on top of the regular semiconductor dot patterns, indicating superposition of a second dominant driving force for pattern self-organization.

[1] C. Anders et al., Phys. Rev. B 87 (2013) 245434.
[2] L. Bischoff et al., Nucl. Instr. Meth. Phys. Res. B 272 (2012) 198.
[3] R. Böttger et al., J. Vac. Sci Technol. B 30 (2012) 06FF12.
[4] R. Böttger et al., Phys. Stat. Sol. RRL 7 (2013) 501.
[5] L. Bischoff et al., Appl. Surf. Sci. 310 (2014) 154.