GaN:C　films　are　grown　on　sapphire　by　metal-organic　chemical　vapor　deposition　(MOCVD)　with　different　carrier　gas　and　different　CCl4　source　flux.　To　get　a　high　resistance　(or　semi-insulating)　GaN,　the　electrical　properties　of　GaN　films　influenced　by　CCl4　flux　and　carrier　gas　are　investigated.　The　results　show　that　the　CCl4　flux　and　carrier　gas　influence　the　growth　of　high　resistance　GaN　greatly.　The　sample　A2　gets　the　highest　sheet　resistance　(2.8×107　Ω/sq)　with　the　CCl4　flux　of　0.016　mmol/min　and　N2　used　as　the　carrier　gas.　The　atomic　force　microscope　(AFM)　test　show　that　the　samples　have　a　flat　surface　morphology,　the　roughness　is　around　0.3　nm.　Meanwhile,　it　also　show　that　the　doping　C　has　little　influence　on　the　surface　morphology.　The　low　temperature　photoluminescence　(LTPL)　test　show　that　the　yellow　luminescence　is　related　with　edge　dislocation.　©,　2015,　Science　Press.　All　right　reserved.