ABSTRACT

When the device size becomes small, quantum eects start to emerge. To control electrons in a quantum mechanical manner goes back to the idea of “superlattices and quantum wells” proposed by Leo Esaki in the late 1960s (Esaki and Tsu 1970). In the quantum well, electrons are conned in one direction (growth direction) and now, it is possible to conne electrons in three dimensions (quantum dots). In the superlattices, he tried to realize the minigap with which electron oscillations in the k-space were

explored (Bloch oscillations). is route to conne electrons in a small space has been pursued with the idea that device characteristics of transistors and lasers would be improved due to the modication of the density of states (Arakawa and Sakaki 1982; Sakaki 1982).