This book helps students and researchers who are working in the field of semiconductor devices and technologies. This book reviews hot carrier effects in 2D polar semiconductors (quantum wells), with special emphasis on the GaAs system due to its higher electron mobility and direct wider band-gap. After briefly introducing the basic concepts of electron transport mechanism, we discuss theoretical calculations of current density-channel voltage characteristic for hot electrons in this quantum well structures at different lattice temperatures, namely 27K,50K, 77K and 120K on a displaced Maxwellian model, incorporating deformation potential acoustic and polar optic phonon scattering. The results are obtained from our calculations for quantum well size 100 Å. The electron mobility variations with these temperatures are also shown.