Research On Bonding Performance Of Different Terminal Diamond/Metal Interface

Diamond has attracted wide attention in the field of microelectronic devices because of good physical and chemical properties.The study found that different surface modified diamond films exhibit different electrical conductivity,electron affinity and wettability.These characteristics make it have great application value in planar microelectronics and micro electrochemical devices.In the application of microelectronic devices,Ohmic contacts between metal and diamond play an important role in the performance of devices.The contact interfaces with different metals show different binding properties and electrical properties.The hydrogen terminal diamond is easy to form Ohmic contact with metal because of its good conductivity,while the oxygen terminal is easy to form Schottky contact with metal.A good Ohmic contact between metal and diamond plays a crucial role in the research and development of microelectronic devices.The strength of adsorption between metal and diamond determines whether the surface has good electrical conductivity directly.However,the adsorption capacities between different metals and different terminal diamond surfaces are different.It is very important to explore the adsorption properties of different metals on diamond surface and find the best Ohmic contact metal.In this paper,the binding energy of different metal-diamond surfaces were discussed by theoretical calculation.Diamond surfaces terminated with hydrogen,oxygen and amidogen were prepared through experiments,and gold nanoparticles were adsorbed on the surfaces.The results are of theoretical significance to study the adsorption properties of metal on diamond surface.In terms of theoretical calculation,the hydrogenated diamond(100)and oxygenated diamond(100)surface were built based on density functional theory first principles method,and one layer of metal(gold,copper,aluminum,tungsten and titanium)atoms were adsorbed on the hydrogenated diamond(100)and oxygenated diamond(100)surface.The equilibrium geometries of different models were calculated,and the binding energy between metal and substructure were analyzed by calculating the adsorption energy,the electronic localization function and the atomic populations.The results show that:1)For hydrogenated diamond(100),gold,copper and aluminum adsorption model,the geometric structure are not changed significantly,the adsorption energy is very low,basically no charge transfer occurred,do not have good adsorption capacity.In the tungsten and titanium models,the surface metal atoms have obvious relaxation phenomenon after geometric optimization.The adsorption energy and charge transfer have a certain increase compared with the gold,copper and aluminum models,and the adsorption capacity is stronger than gold,copper and aluminum models.2)For oxygenated diamond(100),compared with the hydrogen terminal,the distance between metal atom layer and oxygen atom layer is far away from the distance between metal atom layer and hydrogen atom layer in gold,copper and aluminum models,while tungsten is opposite.Gold and copper adsorption model basically maintain their original lattice structure,while aluminum and tungsten adsorption model have obvious relaxation.The adsorption energy calculation shows that the adsorption energy between tungsten and oxygen terminal surface is 40.eV,and has strong binding energy.The binding energy of gold,copper and aluminum adsorption models is weak.For the experiment,hydrogenated,oxygenated and ammoniated diamond surfaces were prepared by hydrogen atmosphere heating method,concentrated acid boiling method and silane coupling agent method respectively,and then the gold nanoparticles that average diameter is 18nm were adsorbed on the surface of different terminal diamond by electrostatic force induced self-assembly method.The surface morphology and composition of different modified diamond films were characterized.The results show that the gold nanoparticles were adsorbed on hydrogenated,oxygenated and ammoniated diamond surfaces,and the ammonia termination surface has a higher coverage.The adsorption capacity of the hydrogen termination is weak,and very few gold nanoparticles were adsorbed on the surface of oxygen.