Impact of contact resistance on the transconductance and linearity of graphene transistors

Abstract

Interest in graphene device physics and technology has been growing rapidly, especially for very high frequency transistor applications. However, the predicted intrinsic performance has not been fully realized due to impurity and parasitic issues introduced in device fabrication. Through a self-consistent model, we show that the normalized contact resistance has an exponentially detrimental impact on the peak transconductance, which is a defining transistor parameter. In addition, we reveal that very high current-gate voltage linearity or input invariant transconductance can be achieved in the limit of negligible contact resistances, a desirable feature for linear electronic systems.

Rapid thermal annealing of graphene-metal contact

“…Particularly for high frequency electronics, 5,9 which require smaller channel length for higher operation frequency, the contact resistance is the main limiting factor affecting the device operation. 5,6 Graphene, which is a zerobandgap semiconducting material, shares common fabrication processes with conventional semiconducting materials; therefore, rapid thermal annealing could also be applied to improve the quality of metal contacts. In this work, we implement rapid thermal annealing of graphene based field effect transistors to reduce the contact resistance.…”

“…4 The quality of metal contacts is an important issue for graphene based electronic devices. [5][6][7][8] The resistance of the graphene-metal junction, known as contact resistance, limits the performance of devices having small channel length. Particularly for high frequency electronics, 5,9 which require smaller channel length for higher operation frequency, the contact resistance is the main limiting factor affecting the device operation.…”

Observation of negative contact resistances in graphene field-effect transistors

“…This resistance is a limiting factor for the performance of electronic devices, and an increasing amount of research has concentrated on this issue. [2][3][4][5][6][7][8] The relative contribution of contact resistance to the total device resistance becomes larger in devices with shorter inter-electrode spacings, i.e., in shorter channel devices. Therefore, contact resistance becomes a predominant factor to consider when attempting to achieve miniaturization and integration of graphene devices.…”

Issues with the electrical characterization of graphene devices

“…There are several challenges deterring the stabilization of graphene device properties, such as hysteresis [15,16], high electrical contact resistance [17][18][19], and poor substrate adhesion. These properties have been studied extensively, but only limited progress has been made so far.…”