Research On Field Effect Transistors And Related Circuit Applications Based On Two-dimensional Layered Materials

As the core electronic components of modern integrated circuits,field effect transistors have been driving the rapid development of the integrated circuit industry for nearly half a century.However,as the device size shrinks to its theoretical limit,the short channel effect causes the device performance of conventional silicon-based FETs to degrade dramatically.Traditional approaches that rely on reducing device size,improving device performance,and increasing device integration density to improve integrated circuit performance will be ineffective.In response to this challenge,researchers are working to find new materials to mitigate the effects of short-channel effects and continue to advance the size of devices.On the other hand,researchers hope to design new-principle electronic devices and explore new ways to calculate information to advance the performance of integrated circuits.The two-dimensional layered material is rich in variety,and its structure is that atoms in the layer form a stable lattice structure by covalent bond bonding,and the atomic layer is combined by van der Waals force.The two-dimensional layered material can be stably present in the form of an atomic thickness film,and its surface has atomic level flatness without the unique property of dangling bonds.The use of twodimensional layered materials to fabricate field effect devices has great significance.On the one hand,due to the inherent characteristics of the atomic thickness of the twodimensional layered material,the device exhibits excellent gate control performance,and the theoretical limit size miniaturization of the device is further developed to the ~3 nm technology node;on the other hand,the rich physical properties of 2D layered materials provide an ideal platform for designing new principle field effect devices.In this thesis,we mainly investigated two kinds of field effect devices based on two-dimensional layered materials,and shows related analog circuits and logic circuit applications.In terms of device-level research,we designed and demonstrated a new principle field effect device,and analyzed the working mechanism of the device.In terms of circuit function applications,we fully exploited and utilized the features of the new principle devices to design and implement related high-performance circuit functions.Our work proves that the research of new principle electronic devices based on two-dimensional layered materials has great prospects for promoting the continuous improvement of integrated circuit performance in the post-Moore era.First,we investigated a vertical field effect transistor based on graphene/ molybdenum ditelluride(Mo Te2)van der Waals heterojunction to exhibit a V-type ambipolar field effect characteristics,and by virtue of energy band diagram and thermal excitation model the working mechanism of the device is explained.Subsequently,we used the unique field effect characteristics of the device to implement two basic analog signal modulation functions,output phase controller and frequency doubler.Then,we focused on the electrical properties of reconfigurable devices based on devices with ambipolar field-effect characteristics.We have designed and demonstrated two kinds of Tungsten diselenide(WSe2)-based reconfigurable field effect devices.One is a symmetric double-gate structure WSe2 field effect adjustable homojunction device.The device exhibits four typical homojunction characteristics,including pn junction,np junction,nn junction,and pp junction,under the regulation of two independent gate voltages.The second is a single-gate regulated reconfigurable field effect characteristic WSe2 field effect transistor device.The device exhibits typical characteristics of dynamic reconfiguration of p-type and n-type field effect characteristics under the external bias voltages of source-drain bias Vds and gate bias Vgs.The devices of these two kinds of structures have their own advantages.The symmetric double-gate structure WSe2 field effect adjustable homojunction device is rich in electrical state,and the single-gate regulation reconfigurable field effect characteristic WSe2 field effect transistor device has a simple structure and is beneficial to realize the device miniaturization.Finally,we have performed a large number of related circuit functions based on WSe2 reconfigurable field effect devices with two structures.Among them,based on the symmetric double-gate structure WSe2 field effect adjustable homojunction device,we first show the high-performance logic inverter based on this type of device.A logicrich logic cell circuit is then designed based on the logic inverter circuit.Then based on the logic unit circuit,we show more complex logic functions(three-input "NAND gate",three-input "NOR gate",three-input "AND-OR-INVERTER gate",three-input "ORNAND-INVERTER gate" ",2:1 data selector,D-latch,1-bit adder and 1-bit subtractor function).And the logic function we show realizes that the voltage range of the input voltage signal and the output voltage signal are consistent,and the signal output of the full swing is realized,which ensures the accuracy of the logic operation.Finally,we also designed a traditional analog signal waveform modulation circuit application and an analog synaptic function circuit application for future neuromorphic calculation based on this type of device.Besides,based on the circuit function display of the singlegate regulated reconfigurable field effect characteristics of the WSe2 field effect transistor device,we combine the unique electrical characteristics of the device with the reconfigurable characteristics and the circuit design concept of the traditional pass transistor logic.A logic circuit with a simple structure and powerful logic expression is realized.Moreover,we also proposed a universal circuit design rule based on this design idea to achieve more complex logic functions.