Fabrication of Patterned Carbon Nanotube Field Emission Surfaces on SiC Substrates

ABSTRACTThis work focuses on the patterning of SiC substrates prior to carbon nanotube (CNT) formation using the surface decomposition growth method for the purpose of improving the field emission capabilities of the resultant CNT film. The thermal decomposition of silicon carbide (SiC) substrates is an established approach to create highly dense arrays of vertically aligned CNTs. The attractiveness of this growth approach is that the CNTs form without the aid of a catalyst metal, yielding potentially defect free CNTs ideal for various applications. Due to the high temperature anneals (1400-1700oC) and moderate vacuum conditions (10−2 – 10−5 Torr) necessary for the thermal decomposition process to initiate on the SiC substrate, patterning CNT outcroppings ideal for enhancing the surface’s field emission properties is more difficult when compared to metal catalyst based chemical vapor deposition growth processes on silicon substrates. The intent of the SiC patterning is to reduce field screening effects between neighboring emission sites during field emission while maintaining a high emission site density. Specifically, the SiC substrate is etched to form μm scale pillars on the SiC surface. Experimental findings show that SiC substrates patterned with μm scale pillars can be decomposed to form CNT topped field emission sites, yielding a field emission substrate that outperforms a non-patterned SiC/CNT film. A turn-on electric field of 4.0 V/μm was measured.