Introduction

Abstract

In the history of modern physics and engineering, the electron quantum mechanical effect and its utilization in electronics have attracted much attention. With increase in demand for ultrahigh sensitivity of signal sensing, ultrahigh speed of data processing, ultralow power dissipation of computer components and so on, quantum effect electronics has become more and more promising. Since the middle of the twentieth century most of vacuum electronics have been replaced by the solid state electronics, where the electron dynamics are well described by the band-diagram description. Solid state electronics itself and band-diagram description were originally in the category of quantum mechanics. However, the treatment of carriers based on the band-diagram inside semiconductors used the classical model where the electron wave concept has been missing. One should perceive it to be also true even for semiconductor superlattices. In the late twentieth century, along with the extremely miniaturized scale of semiconductor devices, mesoscopic physics and mesoscopic electronics have boomed. In this research area, one attempts to manipulate directly the coherent electron wave instead of the electron particle. In ordinary semiconductors, however, only the nanoscale dimension allowed us to handle electron wave interference, interaction and so on to some extent. Besides, success was obtained only at cryogenic temperatures. Collisions between electrons or between electron and lattice (or impurity) was recognized again as a forcible enemy of electron wave engineering. It was a time when both researchers and engineers in the field were urged forward to search for better physical and engineering stages where no electron collisions take place thereby maintaining electron wave coherency over very long distances in the appropriate temperature range.