The Preparation of II–VI Semiconductor Nanomaterials - Semiconductor Quantum Dots: Organometallic and Inorganic Synthesis - page 30

d n 1 y 4 n g | 1

d n 4 .

Figure 1.5 Cartoon showing model of a CdTe tetrapod, with the di ering crystalline

regions. Reprinted by permission from Macmillan Publishers Ltd: Nat.
Mater. , L. Manna, D. J. Milliron, A. Meisel, E. C. Scher and A. P.
Alivisatos, Nat. Mater. , 2003, 2, 382. Copyright 2003.

The selective growth of metal tips on to rods and tetrapods is a notable goal
due to the potential to nanoparticles into nanoelectronic circuitry. The

highly reactive terminal facets of the rods and tetrapods described make
them ideal for such structures. This has been achieved by the addition of
gold chloride and dodecyldimethyl ammonium bromide (DDAB) to a toluene
solution of anisotropic dots. 192 During the reaction, the rods react with the
DDAB and become smaller due to a dissolution process. The tipped materials
resembled dumbbells and a study of the Au

' wire '

CdSe interface inferred the
presence of covalent bonds between the two phases, essential for e

-

cient
electrical connectivity. The electronic structure of CdSe/gold nanorod
dumbbells has been investigated. 193 Although there was evidence of growth
on other parts of the rods, this could be controlled by altering the amount of
gold precursors. The dumbbells could be self-assembled by adding thiolated
biotin to the gold terminals, which were then linked together by avidin,
a protein which can accommodate up to four biotin units, yielding ower-like

and end-to-end assemblies. 194 Gold has also been grown on CdSe/CdS seed/
rods, where the gold



' island ' was found to grow at the position of the CdSe

seed. 195