Production and Characterization of Coating-Substrate Combinations for Sustainable Ceramic Data Storage Media

Abstract

Nowadays, data storage and its sustainability are topics of great importance, not only for cloud providers but also for other companies and even for people in their personal lives. Most of the data stored is referred to as cold data, meaning it is very rarely changed and accessed (e.g., photos, research results). That cold data is currently stored by running server farms utilizing hard drive discs (HDD). Thereby, cloud providers make the data available for their users. These server farms need a lot of energy, and the storage capacity is very limited, which due to increase of needed capacity makes them very insufficient. To overcome the issue of the high amount of required energy and limited capacity, a new form of storage media is in the focus of our research. By utilizing a certain coating-substrate combination, it is possible to literally write data into ceramic data carriers using a femtosecond laser. By applying this method, it is possible to write a large amount (14 GB) of data onto a relatively small area (100 cm²) of the ceramic data carrier. Within our research we analysed different coating-substrate combinations regarding their mechanical properties and laser ablation characteristics. The coatings investigated were synthesized by magnetron sputtering and argon nitrogen gas mixture using different composite targets e.g., Ti, Cr, CrB2, AlCr, and AlCrNbTaTi. The coatings were deposited on different substrates including sapphire, silicon, glass, and austenitic steel. All the coatings were investigated by XRD showing a single-phase fcc-structure and hardness values ranging from 21 to 33 GPa. After investigating structure and mechanical properties, laser ablation tests were conducted to determine the laser ablation threshold and to find suitable coating-substrate combinations for the aimed application. Furthermore, after writing data into the samples, the samples were tested regarding their thermal stability, oxidation and corrosion resistance. These studies prove the exceptional stability and durability of such ceramic data storage media. Once written, storing the data does require almost no energy and allows to save up to 99 % of the currently used energy for data storage.