Other Semiconductor Materials

In the UV most of the materials of interest, e.g. Si, polysilicon, SiGe, GaAs, and other semiconductor materials, are strongly absorbing this enables surface-sensitive measurements. Surface roughness, native oxide covering, material composition, and structural properties can be analyzed. 

The electronic properties of silicon and other semiconductor materials are shown in Table 13.2. 

Although silicon cannot compete with other semiconductor materials in specific areas, it is overall an excellent material, a fact amply shown by its dominance of the market for the last forty years. It is readily available with a high degree of purity and relatively low cost. Most IC s are made from silicon and this is likely to remain so for some time. 1 1... 

Various other semiconductor materials, such as CdSe, MoSe, WSe, and InP were also used in electrochemistry, mainly as n-type photoanodes. Stability against photoanodic corrosion is, naturally, much higher with semiconducting oxides (Ti02, ZnO, SrTi03, BaTi03, W03, etc.). For this reason, they are the most important n-type semiconductors for photoanodes. The semiconducting metal oxide electrodes are discussed in more detail below. 

The partial oxidation of conjugated polymers is generally referred to as p-doping, again in analogy to other semiconductor materials, but the basic process is the removal of electrons as in any other branch of chemistry, i.e.,... 

Visible- or solar-blind UV sensors can be made from a Si photodiode by additionally using an optical filter that transmits UV radiation only, see below. A more detailed explanation of the physics of UV photodiodes (made from Si as well as from other semiconductor materials) can be found in Ref. [1]. 

Mass spectrometry is also extremely useful as a process monitor. Less sophisticated residual gas analyzers (RGA) operating on the principles of mass spectrometry are available for these purposes and for end point detection. For the etching of Si 128-130), poly-Si 130), silicon nitride 130), and Si02 (729), SiF (m/e=85) has been shown to be effective for end-point detection. In addition, (m/e=14) is useful for nitride 129,130) in leak tight systems, while O (m/e =16), CO (m/e =44) and Si" " (m/e=29) are useful for oxide (757). Because of the general nature of mass spectrometry as a diagnostic tool, it should be applicable to etching studies of metals and other semiconductor materials. 

The temperature dependent 1-V characteristics of BiSbTe (BST) nanowires showed the nonlinear behaviour, suggesting formation of Schottky contacts between electrode and bundled of nanowires. Despite of comprehensive experimental data, the observed peculiarities of 1 V characteristics in [3] remained without explanation. We note here that the temperature variation of nonlinear I-V characteristics presented in [3] are similar to the observations in other semiconductor materials and have been properly explained in [1,2] invoking the model. Therefore, in this work we attempt to give an explanation for the temperature behaviour of conductivity and the I-V characteristics in BST nanowires on the basis of the PhAT model. 

Judging by the present trend it is apparent that more innovative use of SPM-based oxidation of Si and other semiconductor materials will be applied in nano-electronic device fabrication. 

Electrosynthesis of semiconductors such as epitaxial GaAs and other semiconductor materials with high value would be attractive candidates for improved processing by electrochemical techniques. Materials such as HgCdTe (IR sensors), CdTe, CdS, and CdSe (photoelectrochemical and photovoltaic devices) would enjoy much wider application if less costly production could be achieved. Current electrochemical technology for such applications is embryonic, and most semiconductor materials now made with these techniques are inferior in properties compared to those available from other preparation methods. An improvement that is most needed is the ability to deposit single crystals of macroscopic size and of controlled expitaxy. 

Ductile grinding of ceramics is the focus of Chapter 1 by Professor Eda of Ibaraki University in Japan. His laboratory is well known mainly for new methods and tools for machining of ceramics and other semiconductor materials. Chapter 2 comes from Kmnamoto University. Over the years. Professors Yasui and Matsuo developed special techniques for grinding fine ceramics using diamond wheels with coarse grains. 

Excellent linearity of output current as a function of incident light Spectral response from 190 to 1,100 nm (silicon), longer wavelengths with other semiconductor materials... 

Devices based on a-SiC H have certain advantages over other semiconductor materials in a number of applications in optoelectronics, such as thin-film light-emitting diodes, coatings for laser facets, and a broadband window material for amorphous solar cells [163-165], These applications exploit the fact that the optical energy gap and the refractive index of the films can be varied by changing their chemical composition. 

The promising electronic properties of beta-silicon carbide are compared to those of other semiconductor materials in Table 8.3 of Ch. 8. A major advantage of this material is its high-temperature potential (>1000"C) which far surpasses that of other semiconductors. Beta-SiC should also be more effective than silicon or gallium arsenide particularly in microwave and millimeter-wave devices and in high-voltage power devices. The development of SiC as a semiconductor is still in the laboratory state. 

Rgure 11.15. Electron-carrier mobility of diamond and other semiconductor materials. 

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