The Preparation of II–VI Semiconductor Nanomaterials

Abstract

Although nanoparticles (notably metals) can be traced to antiquity, the origins of modern semiconductor quantum dots (QDs) is a much later development. Specic advances in quantum-conned semiconductor particles can be traced to Grätzel, 1 who reported the synthesis of colloidal CdS to examine photo-corrosion, and Brus 2 who notably reported the band edge luminescence of the same material. At approximately the same time, Ekimov reported quantum connement in CuCl prepared in a silica glass, 3,4 while Henglein, an early pioneer of colloidal semiconductors, reported the synthesis of CdS on colloidal SiO 2 . 5 Fendler then reported the use of a reverse micelle to prepare CdS nanoparticles, 6 which was importantly improved on by Henglein, who used polyphosphates as a well-dened passivating agent, allowing nanoparticles to be processed and redispersed. 7The work described above utilised mainly inorganic salts as precursors in aqueous-based reactions. Consequently, the low temperatures used and the presence of air and water oen resulted in polydispersed materials with relatively poor optical and crystalline properties. The small number of available suitable precursors also reduced the number of systems that could be explored. The need to improve these reactions by removing air and water dictated the use of organic-based starting materials; however, inorganic reagents such as Na 2 Se could not easily be used in organic solvents so alternatives were required.Independently, Steigerwald pioneered many of the early chemical routes to bulk solid-state materials, 8 inspired by the early work on the deposition of