High-Conductivity Stoichiometric Titanium Nitride for Bioelectronics

Bioelectronic devices such as neural stimulation and recording devices require stable low-impedance electrode interfaces. Various forms of nitridated titanium are used in biointerface applications due to robustness and biological inertness. In this work, stoichiometric TiN thin films are fabricated using a dual Kaufman ion-beam source setup, without the necessity of substrate heating. These layers are remarkable compared to established forms of TiN due to high degree of crystallinity and excellent electrical conductivity. How this fabrication method can be extended to produce structured AlN, to yield robust AlN/TiN bilayer micropyramids, is described. These electrodes compare favorably to commercial TiN microelectrodes in the performance metrics important for bioelectronics interfaces: higher conductivity (by an order of magnitude), lower electrochemical impedance, and higher capacitive charge injection with lower faradaicity. These results demonstrate that the Kaufman ion-beam sputtering method can produce competitive nitride ceramics for bioelectronics applications at low deposition temperatures.

Automated summary

In this study, stoichiometric TiN thin films were successfully fabricated using a dual Kaufman ion-beam source setup without substrate heating, resulting in high crystallinity and excellent electrical conductivity. Structured AlN was also produced using this method to obtain robust AlN/TiN bilayer micropyramids with superior performance metrics compared to commercial TiN microelectrodes important for bioelectronics interfaces. These results demonstrate the potential of the Kaufman ion-beam sputtering method for producing competitive nitride ceramics at low deposition temperatures for bioelectronics applications.