Behind the current versus voltage characteristics of any semiconductor device, there is a transport problem describing how electrons are injected at some electrodes and collected at some other electrodes. Electrons in the semiconductors are driven by the electric (and magnetic) field, and the electrostatic potential is in turn affected by the carrier densities. Hence the transport and electrostatics equations usually must be solved self-consistently, which demands a numerical approach. The geometrical scaling of the devices and the development of 3-D device architectures has further complicated the picture, in that the tiny device features result in size-induced quantization effects. Moreover, quantum effects can occur also in the transport direction, both in MOSFETs and in tunnelling devices.

For more than twenty years our group has been engaged in numerical models for electronic transport in nanoelectronics materials and devices. Our expertise covers TCAD commercial tools, as well as the in-house development of our own simulators. We have developed electron device simulation tools based on the semi-classical Boltzmann Transport Equation (BTE) solved with either statistical methods (e.g. the Monte Carlo approach) or deterministic methods, and for device architectures ranging from conventional bulk MOSFETs to nanowire and nanosheet Gate All Around FETs.

More recently we have extended our know-how to quantum transport based on the Non Equilibrium Green’s Function (NEGF) method, in collaboration with Marco Pala. The Hamiltonian models that can be used in our NEGF simulations range from a simple effective mass approximation approach, to the Density Functional Theory (DFT) Hamiltonians employed in the ab-initio solver  Quantum ESPRESSO. The computational burden increases dramatically when moving towards more physically sound models, which makes it necessary the use of High Performance Computing resources.