An electron-emitting device contains a vertical emitter electrode patterned into multiple laterally separated sections situated between the electron-emissive elements, on one hand, and a substrate, on the other hand. The electron-emissive elements comprising carbon nanotubes are grown at a temperature range of 300.degree. C. to 500.degree. C. compatible with the thermal stress of the underlying substrate. The electron-emissive elements are grown on a granulized catalyst layer that provides a large surface area for growing the electron-emissive elements at such low temperature ranges. To ensure growth uniformity of the carbon nanotubes, the granularized substrate is soaked in a pre-growth plasma gas to enhance the surface diffusion properties of the granularized substrate for carbon diffusion.