Semiconducting device structure

Fig. 4.1 Device structure of an LED fabricated from semiconducting and metallic polymers.

Semiconducting silicides epitaxially grown on silicon have gained an increased practical interest to be used in novel semiconducting devices due to their high thermal stability, homogeneous interface and smooth surface morphology [1]. Lowdimensional structures are the main object of study and application in nanoelectronics. When the structure size in one direction decreases up to several run, its properties may differ essentially from the bulk properties of a source material. Such modification of the properties looks attractive. 

For example, finer resolution can be achieved by an appropriate patterning and structuring of the substrate prior to printing. This is essential for the fabrication of pol mier-based semiconducting devices (11). 

The experiment by Jenekhe and coworkers demonstrated that below a critical thickness of the semiconducting polymer structure, the optoelectronic device exhibits a three-fold enhancement in the photoconductivity and allows for voltage-tunable... 

The prime objective of this chapter is to explore the electrical properties of materials— that is, their responses to an applied electric field. We begin with the phenomenon of electrical conduction the parameters by which it is expressed, the mechanism of conduction by electrons, and how the electron energy band structure of a material influences its ability to conduct. These principles are extended to metals, semiconductors, and insulators. Particular attention is given to the characteristics of semiconductors and then to semiconducting devices. The dielectric characteristics of insulating materials are also treated. The final sections are devoted to the phenomena of ferroelectricity and piezoelectricity. 

Studies on the electronic structure of carbon nanotube (CNT) is of much importance toward its efficient utilisation in electronic devices. It is well known that the early prediction of its peculiar electronic structure [1-3] right after the lijima s observation of multi-walled CNT (MWCNT) [4] seems to have actually triggered the subsequent and explosive series of experimental researches of CNT. In that prediction, alternative appearance of metallic and semiconductive nature in CNT depending on the combination of diameter and pitch or, more specifically, chiral vector of CNT expressed by two kinds of non-negative integers (a, b) as described later (see Fig. 1). 

Polyfarylene vinylene)s form an important class of conducting polymers. Two representative examples of this class of materials will be discussed in some detail here. There are poly(l,4-phenylene vinylcne) (PPV) 1, poly(l,4-thienylene viny-lenc) (PTV) 2 and their derivatives. The polymers are conceptually similar PTV may be considered as a heterocyclic analog of PPV, but has a considerably lowci band gap and exhibits higher conductivities in both its doped and undoped stales. The semiconducting properties of PPV have been shown to be useful in the manufacture of electroluminescent devices, whereas the potential utility of PTV has yet to be fully exploited. This account will provide a review of synthetic approaches to arylene vinylene derivatives and will give details an how the structure of the materials relate to their performance in real devices. 

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