Native Oxide Layer Role during Cryogenic‐Temperature Ion Implantations in Germanium

• Published in: Physica status solidi. A, Applications and materials science Applications and materials science, 2024-12, Vol.221 (24), p.n/a
• Main Authors: Caudevilla, Daniel, Pérez‐Zenteno, Francisco José, Duarte‐Cano, Sebastián, Algaidy, Sari, Benítez‐Fernández, Rafael, Godoy‐Pérez, Guilleromo, Olea, Javier, San Andrés, Enrique, García‐Hernansanz, Rodrigo, del Prado, Álvaro, Mártil, Ignacio, Pastor, David, García‐Hemme, Eric
• Format: Article
• Language: English
• Subjects: Chemical composition; cryogenic; Cryogenic temperature; Diffusion layers; Germanium; Germanium oxides; hyperdoping; Ion implantation; ion implantations; Laser beam melting; Liquid nitrogen; Room temperature; Silicon substrates; Tellurium; Temperature
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.202400124

Herein, the structural properties and chemical composition of Ge samples implanted with tellurium at cryogenic temperatures are analyzed, focusing on the role of the native oxide. For germanium, cryogenic‐temperature implantation is a requirement to achieve hyperdoped impurity concentrations while simultaneously preventing surface porosity. In this work, the critical role of the thin native germanium oxide is demonstrated when performing ion implantations at temperatures close to the liquid nitrogen temperature. The structural and chemical composition of tellurium‐implanted samples as a function of the implanted dose from 5 × 1014 to 5 × 1015 cm−2 is analyzed. After a laser melting process, the incorporated oxygen is diffused to the surface forming again a GeOx layer which retains a large fraction of the total implanted dose. These detrimental effects can be eliminated by a selective etching of the native oxide layer prior to the ion implantation process. These effects have been also observed when implanting on Si substrates. This work identifies key aspects for conducting implantations at cryogenic temperatures, that are otherwise negligible for ion implanting at room temperature. In cryogenic temperature implantations, the native oxide plays a critical role. Herein, the structural properties and chemical composition of germanium samples implanted with tellurium under different conditions and doses are shown. The results underscore the significance of etching the native oxide layer, as it stops the tellurium‐implanted ions while concurrently incorporating oxide atoms.