RF-low-temperature-PECVD-growth VG And Its Characteristics

Vertical graphene（VG）is a graphene material grown vertically on the substrate.This unique structure makes it have higher mechanical stability,better specific surface area,low contact resistance with substrate and exposed and ultra-thin graphene edge,based on the excellent conductivity,thermal conductivity,chemical stability and high specific surface area of graphene.Shine in field emission,super capacitor,battery,sensor,wearable device and other applications.At present,plasma enhanced chemical vapor deposition（PECVD）is commonly used to prepare VG.Methane and acetylene need to be flushed as carbon source gas,hydrogen,nitrogen,argon or their mixture as buffer gas,and the substrate can be heated to more than 500 ℃ for successful growth of VG.In order to prepare VG efficiently and safely for its wide application in various fields,VG was successfully grown at low temperature by RF-PECVD,graphite paper is used as solid carbon source and argon as buffer gas.VG with neat height,uniform size and no substrate was grown on electronic glass under the condition of argon flow of 10 sccm,RF source power of 2000 W for 30 min and no substrate heating.The morphology of VG prepared under different conditions was characterized and compared by scanning electron microscope,transmission electron microscope and Raman spectrum,and compared with the conventional heating and methane method.In addition,COMSOL was used to simulate the plasma characteristics during the preparation process of VG under different conditions.VG piezoelectric thin films were fabricated with piezoelectric materials.The negative effects of environmental impact and service loss in application were simulated.The ultrasonic influence experiment and bending durability experiment were carried out on VG piezoelectric thin films.By making copper piezoelectric film and commercial silver piezoelectric film and doing the same experiment,comparing the resistance change rate of piezoelectric films of different materials,VG piezoelectric film has the best durability.Because VG piezoelectric film has good durability,VG is selected as electrode and piezoelectric material to make flexible sensor.Using Lab VIEW to write the automatic test program and build the system,the piezoelectric characteristics,impact characteristics,vibration characteristics,swing characteristics and bending characteristics of the flexible sensor are tested.At the same time,the commercial silver electrode flexible sensor is used for comparative experiment.When pressed and blown by the wind,the silver electrode sensor will always have a large signal mutation,while the VG electrode flexible sensor has no signal mutation or small mutation,which can be applied to the acquisition circuit with limited voltage.In the induction of vibration experiment,VG electrode sensor has different response mode from silver electrode sensor,which widens the application range of flexible sensor.VG can detect the bending state of fingers in the finger bending experiment,and has a good application prospect in the field of wearable devices.