Silicon lattice

This form suggests a Hougen and Watson mechanism in which silane and hydrogen atoms occupy sites that must also be used by the silicon being deposited. The primary disposition reaction can be complemented by dopant reactions involving compounds such as AsHs, PH3, and B2H6, which deposit trace amounts of the dopant metals in the silicon lattice. 

The insertion of the oxygen atoms widens the silicon lattice considerably. A relatively large void remains in each of the four vacant octants of the unit cell. In natural cristobalite they usually contain foreign ions (mainly alkali and alkaline earth metal ions) that probably stabilize the structure and allow the crystallization of this modification at temperatures far below the stability range of pure cristobalite. To conserve electrical neutrality, probably one Si atom per alkali metal ion is substituted by an A1 atom. The substitution of Si... 

The remark just made suggests that a natural place to begin our discussion of equilibrium equations is with the occupation of different charge states. Let a hydrogen in charge state i(i = +, 0, or - ) have possible minimum-energy positions in each unit cell, of volume O0, of the silicon lattice. (O0 contains two Si atoms, so our equations below will be applicable also to zincblende-type semiconductors.) To account for spin degener-ancies, vibrational excitations, etc., let us define the partition function... 

Silicon hydrides, in growing amorphous silicon, 22 129-131 Silicon integrated circuits, 19 167 Siliconized coatings, 10 108 Silicon-killed free-machining steels, 24 424 Silicon lattice, 23 35 Silicon-manganese-zirconium, 26 638 Silicon microelectronics, sensor sensitivity and, 22 269... 

Instead of depending on the thermally generated carriers just described (intrinsic conduction), it is also possible to deliberately incorporate various impurity atoms into the silicon lattice that ionize at relatively low temperatures and provide either free holes or electrons. In particular, Group 13 (IIIA) elements ( -type dopants) supply electrons and Group 15 (VA) elements (p-type dopants) supply holes. Over the normal doping range, one impurity atom supplies one hole or one electron. Of these elements, boron (p-type), and phosphorus, arsenic, and antimony ( -type) are most commonly used. When... 

The insertion of the oxygen atoms widens the silicon lattice considerably. A relatively... 

Boron creates an electron deficiency in the silicon lattice resulting in ay>-type semiconductor forp—n junctions. Boron compounds are more commonly used as the dopant, however (see Boron HYDRIDES). 

What happens when a Group III atom, like boron, replaces an atom in the silicon lattice The situation is shown in Figure 18.12. Boron has three valence electrons and can form electron pair bonds with three of its neighbors. It has no electron to pair up with the electron on the fourth silicon atom. We say we have an electron hole in the silicon lattice. 

Figure 9. Examples of point defects in the silicon lattice. (Reproduced with permission from reference 118. Copyright 1988 Noyes Publications.)...

Vacancies and self-interstitials can exist in equilibrium with each other in the silicon lattice. The concentration of each species can be described by equilibrium equations of the following type. 

The recent observations of a reaction of the alcohol with the silicon lattice are in good agreement with the results of Schott, who also found a reaction with alcohol and CaSi2 under similar conditions (see p. 108). 

The silicon raw material can be analyzed by FT-IR spectroscopy. The oxygen and carbon content is determined by comparing the ratios of the oxygen and carbon bands with those of the characteristic phonon absorptions of the silicon lattice (see Fig. 5.1-9 Zachmann, 1987). The measurements are calibrated by a reference wafer of similar thickness and surface condition in order to avoid complicated correction calculations. In a special manufacturing process for integrated circuits. Si wafers are coated with very thin films... 

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