The main purpose of this book is to elucidate the relativistic effects on electronic properties of one-dimensional systems. In this context the authors first discuss in depth about Dirac Equation in one dimension, the properties of nonrelativistic and relativistic transfer matrix and scattering matrix. Based on these two well-known mathematical techniques, the author then develop a complete relativistic theory of impurity sates, resonant tunneling, and Landauer resistance – all of them usually play a vital role in the electron transport of any electronic devices. The technological implication of the results reported in this book is that one can engineer, rather simply, the fabrication of high-speed solid-state devices by considering a heterojunction semiconductor superlattice with some optimum values of device parameters. As it covers important basic theoretical aspects of electronic properties with practical implications to electronic devices like resonant tunneling diodes, this book will be of great value to the students as well as to the researchers working in the area of condensed matter physics and device engineering.