Silicon dopants

The samples of the as-prepared silicon-doped titanium dioxide were examined by the energy-dispersive X-ray (EDX mapping) which was mounted on both the SEM and TEM. The results show that the silicon dopant is homogeneously distributed in the Ti02 matrix, either in the anatase or the rutile modifications. 

HNA (HF, HN03, CH3COOH, and water [8]) is a complex etch system with highly variable etch rates and etch characteristics dependent on silicon dopant concentrations, the mix ratio of the three acids, the presence or absence of water, and even the degree of etchant agitation. The latter is typical of a diffusion-limited chemical reaction. For the same reason, F1NA etches silicon isotropically. 

Conducting polymers can be characterized by a high conductivity when doped with ions (Fig. 6.102). Their conductivity can be reversibly changed by orders of magnitude, by changing the doping level. Unlike silicon, dopants... 

Alternatively, as in Figure 9.9(b), a dopant with one valence electron fewer than the host contributes an impurity band 1 which is empty but more accessible to electrons from the valence band. An example of such a p-type semiconductor is silicon doped with aluminium KL3s 3p ) in which the band gap is about 0.08 eY... 

Oxidation of Silicon. Silicon dioxide [7631-86-9] Si02, is a basic component of IC fabrication. Si02 layers are commonly used as selective masks against the implantation or diffusion of dopants into silicon. Si02 is also used to isolate one device from another. It is a component of MOS devices, and provides electrical isolation of multilevel metalliza tion stmctures (12). A comparison of Si and Si02 properties is shown in Table 1. 

Fig. 1. (a) Silicon (valence = 4) crystal lattice shown in two dimensions with no broken bonds, T = 0 K (b) siUcon crystal lattice with a broken bond (c) sibcon crystal lattice with a siUcon atom displaced by a donor dopant, ie, -doped (valence = 5) and (d) siUcon crystal lattice with a siUcon atom displaced... 

Arsenic from the decomposition of high purity arsine gas may be used to produce epitaxial layers of III—V compounds, such as Tn As, GaAs, AlAs, etc, and as an n-ty e dopant in the production of germanium and silicon semiconductor devices. A group of low melting glasses based on the use of high purity arsenic (24—27) were developed for semiconductor and infrared appHcations. 

When the structure of a metal changes, it is because there is a driving force for the change. When iron goes from b.c.c. to f.c.c. as it is heated, or when a boron dopant diffuses into a silicon semiconductor, or when a powdered superalloy sinters together, it is because each process is pushed along by a driving force. 

A. Muehlbauer, A. Muiznieks, J. Virbulis. Analysis of the dopant segregation effects at the floating zone growth of large silicon crystals. J Cryst Growth 750 372, 1997. 

The molar ratio of the III compound to the V compound is typically l/lO.t ] To obtain the desired semiconductor properties, dopants are added such as zinc (from diethyl zinc) or magnesium (from bis(cyclopentadienyl) magnesium) for p doping, and silicon (from silane) or selenium (from hydrogen selenide) for n doping. 

---