Gap states controlled transmission through 1D metal-nanotube junctions

Abstract Understanding the nature of Schottky Barrier (SB) formed at the metal/1D-semiconductor interface is a scientific challenge for realizing high performance transistors. In this report, we show that electrical transport through the localized states formed at SBs, called the metal induced gap states (MIGS) determine the drain characteristics of CNTFETs with a little or no influence near the ON-state but start affecting the drain characteristics strongly as the OFF-state is approached. The role of MIGS is characterized by tracking the dynamics of the onset bias V 0 ( M ) of nonOhmic conduction in the drain characteristics probed in two different situations: by varying Ohmic conductance by gate voltage V g ( = M ) and temperature T = M . V 0 ( M ) varies with the zero-bias conductance G 0 ( M ) as a power law: V 0 ( M ) ∼ G 0 ( M ) x M with an exponent x M having positive values. The origin of such power law is tentatively suggested as a result of power law variation of effective barrier height ϕ S B with V g . The influence of MIGS on the transport and the power law relations are tentatively explained with the help of a microscopic model. The unexpected scaling behavior seems to be very generic for metal/CNT contact providing an experimental forecast for designing the state of the art carbon nanotube devices.