Ion Implantation: Nanoporous Germanium

• Published in: Surface investigation, x-ray, synchrotron and neutron techniques Vol. 18; no. 4; pp. 834 - 840
• Main Authors: Stepanov, A. L., Nuzhdin, V. I., Valeev, V. F., Rogov, A. M., Konovalov, D. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.08.2024; Springer Nature B.V
• Subjects: Bismuth isotopes; Chemistry and Materials Science; Electron diffraction; Germanium; Ion implantation; Irradiation; Lattice vacancies; Materials Science; Morphology; Nanowires; Pore formation; Single crystals; Substrates; Surface layers; Surfaces and Interfaces; Thin Films; scanning electron microscopy; ion sputtering; implanted surface; ion implantation; ion accelerator; ion dose and energy; current density; ion-penetration depth; surface morphology; nanoporous germanium
• ISSN: 1027-4510; 1819-7094
• DOI: 10.1134/S1027451024700526

The formation of amorphous thin surface layers of nanoporous Ge with various morphologies during the low-energy high-dose implantation by metal ions of different masses, namely 63 Cu + , 108 Ag + , and 209 Bi + , on single-crystal c -Ge substrates was experimentally demonstrated using high-resolution scanning electron microscopy. The structure of the obtained nanoporous Ge layers was studied using backscattered electron diffraction. Under irradiation with low-energy ions, such as 63 Cu + and 108 Ag + , needle-like nanostructures constituting a nanoporous thin Ge layer form on the surface of c -Ge. However when employing havier 209 Bi + , the implanted layer consists of densely packed nanowires. At high ion-irradiation energies, the morphology of the thin surface layers of nanoporous Ge undergoes a sequential transformation in shape from three-dimensional reticulated to spongy as the mass of the implanted ions increased. Such a spongy structure was formed by sparse individual intertwining nanowires. The general potential mechanisms for pore formation in Ge during low-energy high-dose ion implantation are discussed, including the cluster–vacancy mechanism, local thermal microexplosion, and localized heating accompanied by surface melting with effective sputtering.