Section 1 Electronic Devices

Eig. 3. Cross sections of electronics devices used in ICs. (a) NMOS transistor (b) a twin-tub CMOS device on an n-ty e substrate. 

Horizontal laminar flow clean air benches are not BSCs (Section 10.3.4). They discharge HEPA-filtered air across the work surface and toward the user. These devices only provide product protection. They can be used for certain dean activirie.s, such as the dust-free assembly of sterile equipment or electronic devices. These benches should never be used when handling potentially infectious materials. The worker can be exposed to materials on the clean bench. Horizontal clean air benches should never be used as a substitute for, i biological safety cabinet. 

FIGURE 9.5 Top view of 3-a-Si H TFTs 200 dpi AM-PLED back plane. Inset shows single pixel circuit and the top-view and cross-section schematics. (From Kim, J.H., Hong, Y., and Kanicki, J., IEEE Electron Device Lett., 24, 451, 2003. With permission.)... 

Electronic devices such as automatic titrators and digital burets may be used in place of the traditional glass buret and manual titration. Such devices provide electronic control over the addition of titrant and thus, with proper calibration, are accurate, high-precision devices. These will be discussed in Section 4.9. 

In this section, those devices necessary for communication and integration of industrial chemical processing operations, such as electronic controllers, two-way radios, and wireless data communications are discussed. Typically, SCADA systems would also be discussed in this section however, SCADA was discussed in detail in chapter 7. 

Semiconductor lasers have undergone a considerable metamorphosis during the past 30 years. They have grown and developed into a whole range of sophisticated opto-electronic devices. It is beyond the scope of this section to give a detailed description of the different semiconductor lasers, but we shall summarize the basic principles of this type of laser. 

The hydrogen sensitivity of palladinm-oxide-semiconductor (Pd-MOS) strnctnres was first reported hy Lnndstrom et al. in 1975 [61]. A variety of devices can he nsed as field-effect chemical sensor devices (Fignre 2.6) and these are introdnced in this section. The simplest electronic devices are capacitors and Schottky diodes. SiC chemical gas sensors based on these devices have been under development for several years. Capacitor devices with a platinum catalytic layer were presented in 1992 [62], and Schottky diodes with palladium gates the same year [63]. In 1999 gas sensors based on FET devices were presented [64, 65]. There are also a few publications where p-n junctions have been tested as gas sensor devices [66, 67]. 

A.2 Semiconductor Device Fabrication. In this section we investigate the gas-phase synthesis of compounds, primarily semiconductors, that are preferentially deposited on a surface to form a layer called a thin film. This technology can be used to form structural and protective layers of materials described in the previous section, but is used primarily to form thin films from semiconductor materials for electronic devices. Recall from Figure 6.99, for example, that most semiconductor devices are made from layers of appropriately doped compounds. In order to fabricate these devices at ever smaller scales, the layers must be formed in a carefully controlled manner. This... 

If we place n- and p-type semiconducting crystals in contact (a p-n junction), we create a device that conducts electricity preferentially in one direction this is the basis of action of the semiconductor diodes used in the electronics industry, although specially refined silicon (Section 17.8.2) is usually employed rather than Ge. Transistors and electronic chips are designed using similar basic principles—typically with n-p-n or p-n-p junctions. We consider chemical aspects of electronic devices in more detail in Chapter 19. 

In the last section, electron transfer between dendrimers in films was mentioned. This type of hopping is important in thin-film organic devices (see above). How do dendrimers behave in solution Are the paradigms the same Actually, they are not. 

We recently succeeded in using the functional bionic component, PSI, for photonic devices using molecular-level assembly. Two topics are introduced in this section. The first concerns a biophotosensor in which PSI is directly coupled with an artificial electronic device (a field-effect transistor FET) via a molecular wire designed at the molecular level (Fig. 14). The second is a biophotoelectrode composed of PSI, ITO, and a molecular wire. 

A photomultiplier tube is designed so that it gives a short burst of current (s= 106 electrons in 10 ns) when a photon hits it, as discussed in Section 5.3. Since it is an electronic device, it also has noise. 

Silicon is a material of major technological importance since it forms the basis of a vast range of electronic devices such as transistors, microprocessors and solar cells. It is also likely to be used in numerous future technologies including atomic scale devices [17,18], ultra dense storage devices [19], quantum computers [20,21] and hybrid molecular devices [22]. The surfaces of silicon are the most thoroughly studied of all semiconductor surfaces and there are numerous known surface reconstructions [23]. In this section we... 

In summary of this section, it can be said that experimental manipulations and conductance measurements on single molecules are still a big scientific challenge, and a lot of the progress that has been recently made has been achieved for particular substrate/molecule systems and can not be easily transferred to other surface materials or types of molecules. The STM is certainly the most versatile instrument for manipulations and measurements on the nanoscale but it is not very suitable for an integration into nano-electronic devices. New techniques such as mechanically controlled break-junctions will have to be further developed for this purpose in the future. 

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