pronounced difference between graphene grown on the cu foil 170 and cu foil 180 indicates that the quartz tube 140 changes the local environment inside the tube the presence of the quartz tube 140 reduces the carbon supply and creates a quasi static reactant gas distribution which results in large flower shaped graphene grains the reactant gas distribution in the quartz tube 140 is the ratio of ch 4 to h 2 in the atmosphere of the quartz tube and is smaller than the ratio of ch 4 to h 2 that is flown through the cvd chamber the carbon supply is reduced for the cu foil 170 because unlike the cu foil 180 which receives a steady flow of ch 4 gas as it enters open end 120 of quartz tube 110 and exits through the open end 130 the close end of the quartz tube 140 does not allow cu foil 170 to receive a replenished flow of ch 4 as readily as that received by cu foil 180 fig2 a and 2 b are sem images at different magnifications of as grown graphene flowers 210 and 220 grown on cu foil 180 without the quartz tube 140 by using a reduced methane flow rate of 0 5 sccm ch 4 and 25 sccm h 2 at a total pressure of 150 mtorr other growth parameters are the same as the recipe using vapor trapping quartz tube 140 however the shape of flowers was not as uniform as the ones obtained using quartz tube 140 the vapor trapping approach described herein has little variation from run to run additionally the open end 150 of the quartz tube 140 may permit probing of gas species.