Road to Quantum Boxes

Abstract

Quantum wells and superlattices have evolved over the last two decades to become a prominent multi-disciplinary field in condensed matter science. From the first observation of resonant tunneling to the recent realization of the quantum box, in this work we provide a summary description of the historical development of the field, known today as quantum structures. The focus is on the physics aspect with emphasis on important experimental observations that collectively define the field and set its direction of development.PACS numbers: 73.20. Dx, It has been more than two decades since the superlattices and quantum wells were first proposed and realized. This achievement has dramatically changed the landscape of semiconductor research. Indeed, it has opened up a new field in which materials, physics and electronics are pursued in artificially synthesized structures on the scale of atomic dimensions [1]. Quantum states are created with prescribed conflgurations, leading to unprecedented transport, optical and magnetic properties. We show in Table I the multidisciplinary nature of the field, ranging from the preparation and characterization of the structures to the exploration and investigation of new physical phenomena and device applications. Over the years, the field has experienced tremendous expansion and growth and has developed to become a dominant theme in condensed matter science, known today as quantum structures or artificially structured materials or, loosely, nanostructures.The major focus of our interest in quantum structures has been on their physics aspects. This focus will remain in this work as we attempt to look back and give a brief account of its historical development. In Table II some of the important events are shown in chronological order with emphasis on experimental observations. The list is no doubt incomplete in view of the vast, worldwide effort in this field of research and the very large number of reports in the literature. In this table a few items in the development of electronic and optoelectronic devices are also included.In the early 1970's, amid an environment of Skepticism, we started our experimental effort to fabricate ultrathin semiconductor layers in pursuance of the quantum size effect. Guided by the theoretical prediction of a negative-resistance [2], (603)