Screening in semiconductors

M. Lannoo, C. Delerue, G. Allan, Screening in semiconductor nanocrystallites and its consequences for porous silicon. Phys. Rev. Lett. 74(17), 3415-3418 (1995)... 

Several factors detennine how efficient impurity atoms will be in altering the electronic properties of a semiconductor. For example, the size of the band gap, the shape of the energy bands near the gap and the ability of the valence electrons to screen the impurity atom are all important. The process of adding controlled impurity atoms to semiconductors is called doping. The ability to produce well defined doping levels in semiconductors is one reason for the revolutionary developments in the construction of solid-state electronic devices. 

In the chemical process industry it is often used in chlorine/caustic environment in cell covers, outlet boxes, lined pipes (see Figure 4.25), and tanks. In the pulp and paper industries pipes and scrubbers for bleaching agents are lined with ECTFE. Powder-coated tanks, ducts, and other components find use in semiconductor and chemical process industries (see Figure 4.26). Monofilament made from ECTFE is used for chemical-resistant filters and screens.58... 

It is remarkable that the surface potential fall toward its bulk value is a similar exponential function, (4.148) or (4.152), in the semiclassical Thomas-Fermi theory of electronic screening in the Debye-Huckel/Gouy-Chapman theory of ionic screening and at semiconductor interfaces. Here we consider the following issue When two such phases come into contact as in Fig. 4.9, and a potential bias is set between their interiors, how is the potential drop distributed at the interface ... 

The excitation of light from materials stroked by electrons, known from fluorescent screens of TV tubes for example, is called cathodolumines-cence (CL). In semiconductors with a direct band gap, electrons that are excited from the valence to the conduction band can recombine with the holes by emission of radiation, whereas semiconductors with an indirect band gap have a reduced probability of radiative recombination. In semiconductors and most inorganic materials, CL depends strongly on the concentration of dopants, which can either enhance CL by forming luminescence centers for radiative transitions or quench CL by forming centers of nonradiative transitions. 

Table XVI summarizes the band energies at selected points for Si and Ge calculated using the WDA both with metallic screening and with semiconductor screening in the exchange-correlation functional. In this approach, the exchange-correlation energy of an interacting electron system is expressed in terms of the exchange-correlation hole charge n (in Ry units)...

The last distinctive feature of small semiconductor partides is the partial screening of Coulomb interaction which takes dace in semiconductor particles if the particle radius is less than the Debye length for semiconducton... 

A many-electron method to calculate excitation energies in semiconductors and insulators. It uses a Green s function (G) and a screened Coulomb potential (denoted W) to express the so-called self-energy operator. The self-consistent solution of quasi-particle equations containing the self-energy operator gives quasi-particle energies which can be interpreted as... 

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