Graphene, owing to its excellent physical, mechanical, and electrical properties, as well as its outstanding optoelectronic properties, has garnered significant attention. Consequently, it has opened numerous opportunities for various types of future devices and systems. Graphene, a one-atom-thick layer of carbon atoms forming a honeycomb 2D crystal lattice, stands out as one of the most promising candidates in the field of nano- and microelectronics. This review provides an introduction to graphene, detailing its properties and its applications, particularly focusing on its utilization in the realm of Field Effect Transistors (FETs). Specifically, an analytical device model of heterostructure-based FETs is presented, which essentially comprises an array of nano ribbons clad. The model for Graphene Nano Ribbon (GNR) FETs includes Poisson's equation and can be employed to calculate the current-voltage characteristics and spatial distribution of electric potential along the channel.