Optoelectronic nanodevice

The curves in Fig. 1 demonstrate the decrease of PL intensity (quenching) and the red shift of PL maximum with the voltage increased. At the values of electrical field strength E up to 10 V/cm the PL of nanorods is quenched more than PL of QDs. However, the wavelength shift of PL maximum with applied electric field for nanorods increases very weak. Evidently, due to the elongated shape of nanorods, the external electric field effect may differ for S- and P-polarized PL. This property is important for application of this material in optoelectronic nanodevices. To understand reasons of the electric field effect difference between QDs and nanorods, the mechanism of nanorods PL quenching has to be studied. The quantum-confined Stark effect is probably not the single factor in force. 

Progress in technology of nanosized materials has renewed attention to surface-enhanced optical phenomena. The nanoscale metals, which have important applications in snrface-enhanced Raman scattering (SERS) [1], surface-enhanced fluorescence (SEF) [2, 3] and optoelectronic nanodevices are of particular interest. 

Figure 17.8. Illustration of the wide wavelength range of tunable gap sizes of all the silicon- and germanium-based nanotubes discussed herein for possible photoluminescence applications in optoelectronic nanodevices.

Optoelectronic nanodevices that rely on electric field effects in optical absorption and emission provide the ability to be controlled conveniendy using integrated electronic platforms. Semiconductor quantum dots are theoretically expected as an excellent candidate for such optoelectronic nanomaterials to show optical properties strongly dependent on electric field [1]. In the general class of quantum dots, chemically synthesized semiconductor nanocrystals also exhibit electric field effects, for example, as demonstrated in their optical absorption (e.g. the quantum confined Stark effect [2,3]) and in their optical emission as the Stark shift and luminescence quenching [4,5]). 

The formation of nanostructures such as nanodot arrays has drawn a great attention due to the feasible applications in a variety of functional structures and nanodevices containing optoelectronic device, information storage, and sensing media [1-3]. The various methods such as self-assembled nanodots from solution onto substrate, strain-induced growth, and template-based methods have been proposed for the fabrication of nanodot arrays on a large area, [4-6]. However, most of these works can be applied to the small scale systems due to the limited material systems. 

Finally, metal nanopartides are under investigation as elements in future electronic nanodevices they can be used as nanowires, nanoislands and as electron confinements in single electron tunneling devices [33-35]. Therefore, the fabrication of nanopartides with very well-defined sizes and surface properties is particularly important. Molecular films at particle surfaces are essential for specific interactions between nanopartides and macromolecules, between nanopartides and substrates and for the positioning of nanopartides inside nanodectrode arrangements. Nanopartides are also of interest for nano-optoelectronic appUcations due to their spedfic optical properties. For this purpose, the synthesis of nanopartides with very small distributions in chemical composition, size and shape in microreactors is under investigation. 

It is noteworthy that self-assembly of anisotropic nanostructures, such as nanorods or nanowires, into well-controlled hierarchical arrangements represents a challenge in view of the integration of such nano-objects with unique properties within functional nanodevices for optoelectronic, information storage, catalysis, etc. that are frontier areas of research in chemistry and materials science. 

Nanodevices are systems with nanostructured materials that carry out specific functions with either improved performance or new attributes. Recent years have witnessed the emergence of new device paradigms based on nanostructured materials, including nanoelectronic devices, nano-optoelectronic devices, spintronic devices, nanosensors, and drug and gene delivery systems. 

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