A First-principles Study Of The Group-? Chalcogenide Monolayers As Field Effect Transistors And Photocatalysts

The discovery of graphene is an important milestone in the research of new materials.Since then,this series of layered materials represented by graphene has received extensive attention in the past seventeen years.Compared with traditional bulk materials,2D materials have a special structure with several atomic layers,making them shine in the fields of photocatalysis,integrated circuits,and so on.In addition to graphene,such as MoS₂ and phosphorene have attracted wide attention from researchers.At the same time,the 2D group-III chalcogenide compound has a large specific surface area due to its good carrier mobility,suitable band gap and band arrangement position.It has received extensive attention in photocatalysis fields.This paper mainly conducts theoretical simulations and uses DFT calculation method to study the application of the group-III chalcogenide monolayers in the field of FET and photocatalysts.First of all,because the 2D material as the channel material in the FET inevitably involves contact with the metal electrode,this will greatly affect the performance of the electronic device.Therefore,it is very important to form ohmic contact between the metal and the semiconductor.In this research,the FET with graphene as the metal electrode and the group-III chalcogenide monolayers as the channel material were deeply explored,and the three vd Ws of G/InS,G/SIn₂Se and G/SeIn₂Se were respectively investigated.The heterostructures were designed and studied,and the results showed that the Schottky barrier heights(SBH)of the three heterostructures were 0.17 eV,0.31 eV and 0.53 eV,respectively.In addition,the external biaxial strain can significantly modulate SBH.At the same time,by controlling the interface distance,the tunneling barrier can be reduced.At the same time,considering the Schottky barrier and the tunneling barrier,the G/InS heterostructure has the best performance and controllability.Secondly,a suitable band gap,excellent light absorption capacity,good surface activity,and sufficient driving force for redox reactions are the basic requirements for potential photocatalysts.This paper systematically studied the application performance of Ga(In)S_1-xSe_xmonolayers as high-efficiency spontaneous water splitting photocatalysts.The results show that the Ga(In)S_1-xSe_x monolayer has a band gap value of 2.41-3.35 eV,and its band structure arrangement position required for the photocatalytic reaction.The?G of the OER on the surface of the material shows a downward trend,indicating that the moisture analysis oxygen reaction is thermodynamically feasible.Therefore,Ga(In)S_1-xSe_x monomolecular film has good photocatalytic efficiency and is an ideal photocatalyst candidate material.In particular,Janus Ga(In)S_1-xSe_x(x=0.5)can effectively separate electrons and holes due to the internal electric field.Heterostructures can promote the separation of photogenerated electrons and holes when used in semiconductor photocatalysts.Therefore,this paper also systematically studies the photocatalytic performance of GaSe/InS heterostructures and compares them with monolayer materials.It belongs to group-III chalcogenide monolayers,similar to the common Si/Ge heterostructure,similar lattice structure and similar lattice parameters can reduce the surface stress and contact surface defects,so that the heterostructures are easier to form.The band gap is 2.09 eV for the GaSe/InS heterojunction,which is lower than the band gap width of the monolayer material,but it is still within the range of the band gap width required for the photocatalytic reaction.At the same time,the binding energy of photogenerated electrons and holes of GaSe/InS heterojunction is 0.35eV,which is significantly lower than the binding energy of 0.65eV for single-layer GaSe and 0.70eV of InS,indicating the formation of single-layer GaSe and InS materials After the formation of the heterostructure,the separation of photogenerated electrons and holes can be more effectively promoted,so as to achieve the purpose of further improving the photocatalytic efficiency.