简介：Theetchingeffectofammonia(NH3)onthegrowthofverticallyalignednanotubes/nanofibers(CNTs)wasinvestigatedbydirect-currentplasmaenhancedchemicalvapordeposition(DC-PECVD).NH3gasetchesNicatalystlayertoformnanoscaleislandswhileNH3plasmaetchesthedepositedamorphouscarbon.BasedontheetchingeffectofNH3gasonNicatalyst,thedifferencesofgrowingbundlesofCNTsandsinglestrandCNTswerediscussed;specifically,theamountofoptimalNH3gasetchingisdifferentbetweenbundlesofCNTsandsinglestrandCNTs.IncontrasttotheCNTcarpetgrowth,thesinglestrandCNTgrowthrequiresshorteretchingtime(5min)thanlargecatalyticpatterns(10min)sincenanodotsalreadyformcatalystislandsforCNTgrowth.Throughremovingtheplasmapretreatmentprocess,thedamagefrombeingexposedathightemperaturesubstrateoccurringduringtheplasmagenerationtimeisminimized.Highresolutiontransmissionelectronmicroscopy(HTEM)showsfishbonestructureofCNTsgrownbyPECVD.