Electrical Engineering curricula typically only touch the bandstructure of solids early in the introduction of solid state devices. Critical parameters such as bandedges, effective masses, and degeneracies are extracted from the bandstructure; and, the atomistic details of the origin of the abstract band diagrams are typically deferred to the physics or material science department. However, device engineering and material science meet at the nanometer-scale. Device engineers have managed to create structures that have spatial variations on the atomic scale. From a materials point of view this corresponds to a new composite or heterostructure of finite extent. This presentation will highlight for nanoelectronic device examples how the effective mass approximation breaks down and why the quantum mechanical nature of the atomically resolved material needs to be included in the device modeling. Atomistic bandstructure effects in resonant tunneling diodes, ultra-scales Si slabs, Si nanowires, and alloyed quantum dots will be demonstrated in intuitive pictures. The presentation concludes with a brief overview of the empirical tight binding method that bridges the gap between material science, physics, and electrical engineering for the quantitative design and analysis of nanoelectronic devices.
MSEE 239, Purdue University, West Lafayette, IN