Sputtering and amorphization of crystalline semiconductors by Nanodroplet Bombardment

Abstract

In this review we expose how Nanodroplet Bombardment of surfaces by charged particles produced through electrospray atomization offers unparalleled opportunities for surface engineering of chemically inert crystalline materials. The sputtering yields and rates are comparable or higher than reactive etching techniques and significantly higher than other physical sputtering systems. Moreover, bombardment can amorphatize a thin layer of the target. The imposed physical characteristics of the electrospray, droplet diameter, molecular mass of the spray, and kinetic energy will determine the sputtering and amorphization efficiency, and the topography of the processed target. Molecular dynamics studies have clarified the mechanisms of both processes; amorphous layers appear due to ultra-fast quenching of melted target pools around the impact area while sputtering is driven by a combination of collision cascades, thermal evaporation, and, for large and fast projectiles, of hydrodynamic forces.

On the Limits of Scalpel AFM for the 3D Electrical Characterization of Nanomaterials

“…It is also worth noting that scalpel AFM has been also recently used to etch the surface of Si, Ge, and SiGe semiconducting wafers for microelectronics industry (in air atmosphere). [39] While there is no question about the ability of the CAFM tip to scratch any material if sufficient FC is applied (local etching experiments with sharp AFM tips have been done since the 1980s), [40,41] the high pressures applied may induce severe changes on the properties of the materials being etched (e.g., local-heat-induced phase change [42,43] and even material melting [44] ) , which could easily modify the shape and currents driven by different features below the tip apex (e.g., <30 nm wide CNFs). Moreover, the current signals collected during the etching process may compile additional contributions due to the high pressure applied during the scan (e.g., flexoelectricity, [4] thermoelectric currents [44] ), which may result in overestimations of the currents registered.…”