Physical Properties of Semiconductors

The role of electronic theory of chemisorption in developing ideas on effects of adsorption on electrical and physical properties of semiconductor adsorbents. 

In the preceding chapter we pointed to electrical conductivity as one of the physical properties of semiconductors which is changed by a chemisorption process and is accessable to measurement. A further possibility for investigating the mechanism of chemisorption is the relation between the work function and the external electric field of the semiconductor as influenced by chemisorption. These effects have been used for the interpretation of the mechanism of chemisorption and heterogeneous catalysis by Suhrmann (42), and have been experimentally demonstrated in chemisorption processes by Ljaschenko and Stepko. These effects shall here be correlated with our concept of the boundary layer formed in the presence of oxygen and hydrogen. 

C.M. Wolfe, N. Holonyak, G.E. Stillman [ Physical Properties of Semiconductors (Prentice Hall, Eaglewood Cliffs, 1989) ]... 

The values of Vm and are key experimental quantities that are used to characterize the physical properties of semiconductor/metal interfaces. If Vbi or b can be determined, then W, Q, E(x), and most of the other important thermodynamic quantities that are relevant to the electrical properties of the semiconductor contact can be readily calculated using the simple equations that have been presented above. Methods to determine these important parameters can be found in the literature. However, it would be useful at this point in the discussion to consider what values of and Vbi are expected theoretically for a given semiconductor/metal interface. By definition, = (/ip.m - at the electrode surface (Figure 4b). Thus, in principle, the barrier height can be predicted if the energies of the semiconductor band edges and the electrochemical potential of the metal can be determined with respect to a common reference energy. 

Some physical properties of semiconductor electrodes depend on the orientation of the crystal, and surface properties vary from one crystal plane to the other. It is therefore very important in studies of surface and interface effects that the proper surface is selected. A semiconductor crystal can be cut by sawing or by cleavage. Cleavage in... 

Microstructural factors also play important roles in determining the electrochemical and physical properties of semiconductor-electrolyte systems. For example, semiconductor electronic properties are usually interpreted in terms of ideal band models for perfect crystals—i.e., for systems that exhibit absolute long-range order. For many systems, however, this is a gross oversimplification and, in the extreme of the amorphous state, it may be appropriate to abandon band models altogether... 

The physical properties of semiconductors treated in this section are the following ... 

Dislcxation-free silicon single crystals are the basic material of microelectronics and nanoelectronics. Physical properties of semiconductor silicon are determined by the structural perfection of the crystals grown by the Czochralski and float-zone processes (Huff, 2002). In such crystals during their growth are formed grown-in microdefects. 

Physical Properties of Semiconductors, NSM Archive http //www. ioffe.ru/SVA/NSM/Semicond/... 

Thermal conductivities of (a) diamond and (b) cubic SiC. The conductivity of diamond reaches a peak of 12,000 W/m -K at 100 K, 30 times greater than Cu. The thermal conductivities are limited by heat capacity below 100 K and by phonon collisions above 100 K. (Data taken from Adachi, Handbook of Physical Properties of Semiconductors.)... 

Adachi s Handbook of Physical Properties of Semiconductors, Springer, New York, 2004. 

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