TABLE OF CONTENTS Heterostructure is a well-developed concept in semiconductor discipline. To form a heterostructure, materials of different kinds should form a sharp interface. According to the form of the interface and the arrangement of the materials forming the interface, heterostructures may be planar (two-dimensional), spherical (zero-dimensional), or cylindrical (one-dimensional). Thin film heterostructures are widely used, and are the core technology of today's electronic industry. Heterostructures of two-dimensional morphology or thin films are the earliest ones in the concept. The second form is the zero-dimensional structure. The concepts of core-shell structure, core-multiple shell structure, and quantum dot quantum well structure all belong to this family. The zero-dimensional heterostructures have been proposed for more than two decades, and have been extensively investigated. 1 5 The one-dimensional heterostructures have the shortest history. However they are developing rather rapidly, and have attracted much research attention in recent years.
One-dimensional nanomaterials, including nanowires and nanotubes, are the research focus in nanomaterials in recent years owing to their rich physical and chemical properties and wide range of applications including optical, optoelectronic, magnetic, and sensing performances. This has been detailed in several review papers. 6 9 The assembly of the one-dimensional building blocks into complex heterostructures makes it possible for us to tune the energy band structure as desired and realize the complicated functionality of the structure. A sharp interface as thin as atomic thickness could act as an effective barrier to confine the transportation of the charge carriers. Therefore, nanodevices could be realized in the near...
