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Shallow dopant

The neutralization of shallow dopants by hydrogen can also be used to create resistive regions for electrical insulation between different components by using proper masking. Reactivation of neutralized dopants by local heating, using laser beam direct writing for example, can be useful if interconnection pathways are desired. [Pg.518]

In addition to interstitial configurations, implanted atoms can occupy either Si- or C-sites and substitutional incorporation on the correct position to act as shallow dopants is not as straightforward as in Si. Moreover, there are nonequivalent lattice sites of either cubic or hexagonal symmetry in the different polytypes. [Pg.110]

In thick ( 300 pm) crystals of GaN electronic excitons of shallow dopants have been observed in far infrared absorption at 215 cm 1 [44], Interpreted as the ls-2p transition of a residual shallow donor, its binding energy was calculated to be (35.5 0.5) meV. Further modes at 149 and 242 cm 1 have been observed in mixed phase GaN/GaAs in Raman scattering and have been associated with electronic excitations of shallow donors in cubic and sphalerite GaN, respectively [45] see also [46], Far infared absorption at 23.2 cm 1 in magnetic fields has been used to determine the effective electron mass in GaN, m = 0.20 0.005 m, (corrected for polaron effects) in cyclotron resonance [47]. [Pg.55]

Shallow dopant a dopant whose energy level is close to either the valence band or the conduction band Valence band the highest filled energy band in a solid Valence band edge the top of the highest filled energy band in a solid... [Pg.4358]

Figure 6 displays the energy levels of common donors and acceptors with reference to the band edges of two semiconductors. If the energy levels of these donors and acceptors are close to the conduction or valence bands, respectively, they are called shallow donors or acceptors. Dopants with energy levels that are further away from either band are called deep dopants. While ionization of shallow dopants is usually complete at room temperature, ionization of deep dopants generally does not occur at room temperature. Shallow dopant materials are considered primarily in the remainder of this section. [Pg.4367]

Becanse shallow dopant atoms are readily ionized at room temperature, the electron concentration, n, in an n-type semicondnctor is closely approximated by the concentration of donor atoms, N, in the lattice. Rigoronsly, the electron concentration is given by the sum of the electrons thermally generated from the Si atoms and those generated by the thermal ionization of dopants. However, becanse n is so small for most common semicondnctors, n = -F Aj Aj for any reasonable dopant concentration (10 -10 dopant atoms cm ). Similarly, for a p-type semicondnctor, the hole concentration is approximately equal to the acceptor concentration, N. This approximation holds becanse shallow acceptors are essentially all ionized at room temperatme, and the intrinsic hole concentration, p, is generally negligible compared to the number of holes that are generated by the dopants. Clearly, control over the dopant density of a semicondnctor allows the manipulation of the carrier concentrations. [Pg.4369]

Additional attempts have been presented to render hosts with the fluorite and the related pyrochlore structure electronically conductive by doping with mixed-valence and/or shallow dopants. The list of dopant materials examined includes oxides of elements of, for example, Ti, Cr, Mn, Fe, Zn, Fe, Sn, Ce, Pr, Gd, Tb and U. In general, however, the extent of mixed conductivity that can be obtained in fluorite-type ceramics is rather limited, by comparison with the corresponding values found in some of the perovskite and perovskite-related oxides considered in the next section. [Pg.479]

Chapter 1 of the present volume provides the basic concepts related to the properties and characterization of the centres known as shallow dopants, the paradigm of the H-like centres. This is followed by a short history of semiconductors, which is intimately connected with these centres, and by a section outlining their electrical and spectroscopic activities. Because of the diversity in the notations, I have included in this chapter a short section on the different notations used to denote the centres and their optical transitions. An overview of the origin of the presence of H-related centres in crystals and guidelines on their structural properties is given in Chap. 2. To define the conditions under which the spectroscopic properties of impurities can be studied, Chap. 3 presents a summary of the bulk optical properties of semiconductors crystals. Chapter 4 describes the spectroscopic techniques and methods used to study the optical absorption of impurity and defect centres and the methods used to produce controlled perturbations of this absorption, which provide information on the structure of the impurity centres, and eventually on some properties of the host crystal. Chapter 5 is a presentation of the effective-mass theory of impurity centres, which is the basis for a quantitative interpretation... [Pg.479]

By using Eqs. (24) and (25), it is possible to compute, say, the complex admittance versus temperature curves for a nearly arbitrary given density of states g E), which may be compared to experimental data on a-Si H. An illustrative example is provided by the density of states shown in Fig. 16 for a series of nearly discrete (narrow Gaussian) levels of concentration fVj with a dominant 50-me V-deep shallow (dopant) level of concentration Ay. [Pg.36]

If the dopant level is within 2kT of Ec or Ey, it will be (almost) fully ionized at room temperature - this is referred to as a shallow dopant. For deep donors and acceptors, the degree of ionization can be calculated with the following equations ... [Pg.20]

Fig. 2.13 Left Depletion layer width as a function of potential drop across the space charge ( Fig. 2.13 Left Depletion layer width as a function of potential drop across the space charge (<psc) and (shallow) dopant density. Right Corresponding amount of adsorbed surface charges needed to compensate the charges in the depletion layer. The data are calculated for a-Fc203 assuming a static dielectric constant of 25 [39, 40]...

See other pages where Shallow dopant is mentioned: [Pg.82]    [Pg.462]    [Pg.463]    [Pg.464]    [Pg.465]    [Pg.469]    [Pg.487]    [Pg.521]    [Pg.121]    [Pg.210]    [Pg.26]    [Pg.67]    [Pg.447]    [Pg.448]    [Pg.449]    [Pg.450]    [Pg.454]    [Pg.472]    [Pg.506]    [Pg.4369]    [Pg.29]    [Pg.125]    [Pg.114]    [Pg.115]    [Pg.115]    [Pg.4368]    [Pg.114]    [Pg.115]    [Pg.115]    [Pg.187]   
See also in sourсe #XX -- [ Pg.20 ]




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Neutralization of Shallow Dopants in III-V Compounds

Shallow dopant impurities

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