Samsung has developed a graphene transistor that can switch off current without sacrificing mobility in the'on'state.
"Graphene possesses electron mobility about 200 times greater than that of silicon,although current cannot be switched off because it is semi-metallic,"said Samsung's Advanced Institute of Technology."This has become the key issue in realising graphene transistors.Previous research has tried to convert graphene into a semi-conductor[allowing it to be turned off],radically decreasing the mobility."
By introducing a graphene-silicon Schottky barrier,in a variable barrier device dubbed a'barristor',current can be switched on and off by controlling the height of the barrier,said the firm.
An on/off ratio of 105 has been achieved by adjusting the gate voltage to control the graphene-silicon Schottky barrier,and inverters and half-adders have been built on 150mm wafers using p and n versions of the device.
"The Schottky barrier prevents an electric charge to flow from metal to silicon,"said Samsung."Generally,metal-semiconductor junction would have fixed work function and Schottky barrier height,but as for graphene,Schottky barrier height can be controlled through the work function."
Key,Samsung told the journal Science,is an atomically sharp interface between graphene and hydrogenated silicon.
