Improving High Speed Switching Graphene Transistors Using Bandgap Engineering

Abstract

Graphene transistors are considered to be the successors’ of MOS transistors for the next generation of advanced integrated circuits. However, graphene suffers from the absence of energy band gap to experience a semiconductor like characteristics. In order to instigate a bandgap in graphene, several techniques and methods are introduced to beak its symmetry. The most common graphene form is the Graphene Nanoribbon (GNR) sheets. Few techniques have been used to grow GNR sheets. However, the main methods that gave better results are bottom-up techniques mainly based on nanotechnology principles. The present paper deals with the investigation of the bandgap engineering approach targeting an increase in graphene transistors switching characteristics leading to higher maximum frequencies applications. The GNR sheets are synthesized using bottom-up CVD based techniques yielding controlled electronics and physical characteristics. Results obtained on few GNR transistor samples compared to other forms of transistors showed good agreements and found to be close to that of standard silicon devices. Moreover, the GNRFETs frequency response is directly related to the bandgap of the material. It has been evidenced that gap modulation modulates the transistor frequency response. Whereas using other techniques, this cannot be achieved. We have found that small values of gap (100-300 meV) led to high mobility and frequencies of thousands of GHz. However, the edge quality limits the maximum frequencies as it induces traps in the graphene generated gap.