Graphene Nanowalls Growth And Its Application In Detectors

Graphene is a kind of two-dimensional carbon nano-material.Because of its excellent properties,it attracted a huge research interests.Graphene nanowalls(GNWs)are wall-like graphene nanosheets that are oriented vertically on a substrate,which not only has the excellent characteristics similar to planar graphene,but also has larger specific surface area and stronger light absorption capacity due to its vertical structure.In the field of detector,GNWs has great promising applications because of its excellent optical and electrical properties.In this paper,plasma enhanced chemical vapor deposition(PECVD),which is compatible with semiconductor technology,is selected to synthesize GNWs on silicon substrate,and its application in photodetectors and thermoelectric detectors is studied.This paper is supported by the national key R & D plan(No: 2018YFA0209000),and the main research contents are as follows:(1)The GNWs are synthesized directly on substrate by PECVD method.The growth time,growth temperature,gas ratio,gas pressure and plasma parameters were determined.The GNWs were characterized by Raman and SEM.The optimum growth conditions and the growth conditions compatible with the device were determined.At last,the light absorption capacity of GNWs was tested.(2)Designing and fabricating GNWs/Si Schottky photodetectors device arrays on Si which are capable of detecting visible to infrared light.The process of the whole device is compatible with the silicon CMOS process.The key parameters of the device,such as I-V characteristics,specific detection rate,response time and so on,are measured,and the responsivity,barrier height and ideal factor of the device are calculated by data fitting.(3)The GNWs-related thermoelectric detectors are studied.GNWs are combined with metal thermocouple and high doping silicon,respectively.Two thermoelectric detectors are constructed and designed.The response mechanism and characteristics of those two thermoelectric devices are studied.