Carbon　nanotips　were　grown　on　a　silicon　substrate　without　catalyst　by　plasma-enhanced　hot　filament　chemical　vapor　deposition　using　a　mixture　of　methane,　ammonia　and　hydrogen　as　the　reaction　gases.　Due　to　production　of　plasma　during　growing　the　carbon　nanotips,　the　reaction　gases　were　ionized　into　various　kinds　of　ions　and　these　ions　played　different　roles　in　the　process　of　growing　the　carbon　nanotips.　Based　on　different　effects　of　the　ions　and　combined　with　theory　related　to　plasma,　a　model　of　the　self-organized　carbon　nanotips　without　catalyst　was　put　forward.　(c)　2004　Elsevier　B.V.　All　rights　reserved.