A tutorial on the NEGF method for electron transport in devices and defective materials

A tutorial on non-equilibrium Green’s function theory and its applications on nanoscale devices is presented. A stepwise tutorial presentation, starting from the concept of Green’s function to its application on nanoscale FETs is presented in this work. The mathematical implementation of the retarded and advanced Green’s function on the device channel is shown in detail. Also, the partitioning of Green’s function into a source Green’s function, a drain Green’s function, and a device channel Green’s function are shown. The construction of the Hamiltonian matrix by applying a non-interacting tight-binding methodology is shown for device channels with rectangular cross sections and line defects. Mathematical expressions for the transmission function and the terminal currents are obtained. Finally, a brief explanation of the concept of scattering contacts and the NEGF mode space extension is presented. This work is useful for understanding the application of Green’s function on nanoscale devices. Graphical abstract