Quantum Wires and Related Lateral Superstructures

Abstract

In 1975–6, the first proposal was made to introduce a periodic potential V(x) or V(x,y) of mesoscopic scale within the (x−y) plane of two dimensional electron systems (2DES) (Sakaki, 1975–1976). As shown in Figs 1, this concept of lateral superstructures (LASS) or planar superlattices (PSL) is quite general, since such structures allow the creation of a variety of novel electronic states that cannot be achieved in conventional multilayered quantum structures; they range from isolated quantum wires (QWI) and boxes (QB) to strongly coupled QWI/QB arrays, where the formation of true minibands and minigaps is expected. Although the fabrication of LASS was considered extremely difficult, recent developments of microfabrication technology have blessed the LASS concept and the formation of novel quantum states is demonstrated at least at low temperatures, where the coherence length of electrons gets quite long as compared with the characteristic length of LASS.