Research On The Two Dimensional Material Based Field Effect Transistors And Radio Frequency Circuits

Since the discovery of graphene,two-dimensional materials have attracted more and more attention around the world due to their unique properties.Due to the ultra-thin nature of two-dimensional materials,it can make up for the influence of short channel effect,making it possible for future electronics.In this thesis,the commonly used twodimensional materials such as graphene,molybdenum disulfide and so on are presented.We use these materials to fabricate field effect transistors and test their performance.What is more,we use the transistors to fabricate double-balanced mixer,distributed amplifiers and so on.Firstly,a large scale monolayer graphene material was prepared by chemical vapor deposition(CVD)for the fabrication of transistors.The fabrication of radio frequency transistor with graphene as channel is called "inverted process".The buried gate and source drain are prepared first,and then the channel.This process can reduce the damage and contamination to graphene caused by the technological process.That ensures the excellent performance of the transistor.For molybdenum disulfide and other materials,mechanical exfoliation is used to prepare the material.Then use the common way to prepare source drain and gate electrode is used.After testing the performance of graphene field-effect transistors,a double-balanced mixer structure is designed,which can increase the linearity of the mixers through the differential ports.At the same time,the effect of transistor performance inconsistency due to immature process is reduced.Finally,the third-order intercept point of the mixer is 12.7 dBm.At the same time,four stage distributed amplifiers based on graphene transistors are constructed,which can be superimposed by adding all the gain.Due to the lack of band gap,graphene transistors cannot saturate and cannot amplify.The simulation results shows a bandwidth of 3 GHz and a steady gain of 7 dB,which makes a useful attempt for the application of graphene in RF circuits.