Study Of Electron Transport Mechanism In Graphene Based Nanoscale Rectifier Devices

With the quick development of the electron devices,the need for information becomes more stronger and the requirement of the device also becomes more strict.The total trend for information is more quickly,higher quality,which depends on the iniaturization of the device.However,when the electronic devices reach nanoscale,the quantum effects will occur.In addition,the miniaturization of the device size also makes the processing costs continue to increase,so the current further miniaturization of microelectronic device will be close to the limit of development.In order to solve this problem,molecular electronics arises at the historic moment.Based on C60,organic molecules,graphene,carbon nanotubes,boron films and other materials,molecular devices have become the research hot spots of molecular electronics.Many interesting physical properties have been reported,such as:molecular field effect,the effects of negative differential resistance(NDR),spin filtering,giant magnetoresistance effect,the rectifying effect and so on.Using a combination of first-principles density functional theory and the non-equilibrium Green’s function method,we systematically study the electronic structures and electron transport properties of the graphene device doped orderly nitrogen atoms.We mainly discuss the influence on the molecular devices with different doping position and gate voltages.The molecular rectifying behavior are observed.We have investigated the electronic transport properties of devices based on an orderly nitrogen-doped armchair graphene nanoribbon.For the devices,the nitrogen atoms orderly dope in the right panel of the devices.Taking in the different widths of the nanoribbon and the doping position,the calculate resulted show that the structure stability of substituting the edge or center four carbon atoms of the electrode is strong.Obvious rectifying effect can be observed and can be modulated by changing the width of the ribbon or the position of the N dopant.In a word,the 7-AGNR-N(n,6)(n=3,4)devices can be used to build molecular rectifier.We have investigated the electronic transport properties of devices based on an orderly nitrogen-doped armchair graphene nanoribbon under gate voltages.The results show that the gate voltage strongly affects the electronic transport properties of the devices.Strong rectifying behavior is observed and it can be modulated by the gate voltage.The maximum rectifying ratio reaches the order of 106 at a specific gate voltage,which is two orders of magnitude higher than the device without applying a gate voltage.The mechanism for the rectifying behavior was investigated from the calculated transmission spectra,potential drop,and local device density of state.The results indicate that the devices regulated by the gate voltage can potentially be applied to high-performance rectifiers,this is because gate voltages can shift energy level and the state distribution of the electrode under energy matching region.