Local synthesis of carbon nanotubes for direct integration in Si microsystems – design considerations

Abstract

The integration of nanomaterials such as carbon nanotubes (CNTs) into microsystems is highly desirable, in order to make use of the unique nanomaterial properties in real devices. However, the CNT-to-microsystem integration is challenging to implement in a manufacturable, cost-effective industrial process. This paper presents our work towards a process for making complete, integrated CMOS / MEMS systems with integrated CNT. We demonstrate the feasibility of the process, using room-temperature processing, low-cost equipment and consumables, and electrical control with automation possibilities. CNTs are directly integrated at the desired positions in the Si microsystem, forming closed Si / CNT / Si circuits. We explore different designs with the aim to obtain uniform and well-defined CNT synthesis conditions, and show that simplified designs can perform comparably to more complex ones. The Si / CNT / Si circuits obtained can show rectifying (Schottky-like) or near-ohmic behavior. Gas sensing possibilities are demonstrated, indicating the possibility of monitoring aging/ fermenting of food. Functionalization of CNTs is demonstrated, using thermal evaporation of Sn and Pd, opening for selective and sensitive sensors for various gases and analytes. Detailed microscopic characterization of the obtained CNTs are presented.

Keywords

Micro/ nano system integration / Carbon nanotubes (CNTs) / Nanoscale assembly / Gas sensors