Method for making carbon nanotube-based device

A method for making a carbon nanotube-based device, the method comprising the steps of:

• providing a substrate with a shadow mask layer formed thereon, the shadow mask layer being configured for defining an unmasked surface area on the substrate;
• rotating the substrate around an axis;
• forming a catalyst layer comprising at least one catalyst block on the unmasked surface area of the substrate, a thickness of the at least one catalyst block being gradually decreased from a first end thereof to an opposite second end thereof, and the at least one catalyst block having a region with a thickness proximal or equal to an optimum thickness at which carbon nanotubes grow the fastest, a thicker region having a thickness that is thicker than the optimum thickness, and a thinner region having a thickness that is thinner than the optimum thickness, such that the carbon nanotubes in the thicker and thinner regions grow slower than the carbon nanotubes at the region;
• introducing a carbon source gas;
• and
• forming at least one carbon nanotube array extending from the catalyst layer using a chemical vapor deposition process, wherein the at least one carbon nanotube array comprises of at least two arc-shaped sections, and each section bending in a direction deviating from the region.