| AVS 62nd International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Thursday Sessions |
| Session NS+MN-ThM |
| Session: | Nanopatterning and Nanolithography/Nanoscale Mechanics |
| Presenter: | AngélicaGuadalupe Hernández, CINVESTAV-IPN, Mexico |
| Authors: | A.G. Hernández, CINVESTAV-IPN, Mexico Y. Kudriavtsev, CINVESTAV-IPN, Mexico |
| Correspondent: | Click to Email |
We have investigated formation of patterned surfaces after low energy oxygen (O2) ion sputtering on germanium (Ge) crystals implanted with silicon (Si) ions and subsequent thermal annealing by using Atomic Force Microscopy (AFM).
A commercially available Ge crystal wafer was implanted with Si+ ions. The energy of implantation was 25 keV. This low energy and the high dose regime (2x1016 cm-2) results a relatively high Si concentration obtaining at the implanted maximum of 5.3x1021 atoms/cm3. Distribution and depth near-surface of implanted ions were calculated by Montecarlo simulations using TRIM software as 15 nm and confirmed by the Secondary Ion Mass Spectrometry (SIMS).
After ion sputtering a study of the surface morphology was performed by AFM for comparison of the obtained results with the Ge surface without implantation. In other hand, Raman spectra of the as implanted samples shows the vibration modes of α-Ge, c-Ge, Ge-Si, α-Si and Si-Si, which is an indicator of Si clusters formation in to the Ge bulk due to the ion implantation.
In order to recover the crystallinity of the Ge lattice, the thermal annealing at 700 ºc during 5min under nitrogen (N2) atmosphere was performed. The corresponding Raman spectra shows the transition from amorphous to crystalline Ge.
After the thermal process, ion beam sputtering was performed by using O2 ions and energy beam of 0.5, 1 and 2 keV at different ion doses under ultra-high vacuum conditions (base pressure ~10-9 mbar). Due to the differences in the sputtering yield between Ge and Si, the preferential sputtering of Ge results in an enrichment of Si on the surface. The Si nano-crystals produces an effect of "shadow" leading to a formation of nano-structured surfaces. This results were compared with our previous work, where Ge surfaces (not implanted) were bombarded under the same sputtering conditions (ion specie, energy and ion dose).
Morphology of the surface was investigated by AFM of the original surface, as implanted samples, thermally treated and after ion bombardment. Finally, we compared the experimental morphology with ones obtained previously by the oxygen sputter Ge crystal.