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Semiconductors donors

Figure 6.1 Schematic band structures of solids (a) insulator (kT ,) (b) intrinsic semiconductor (kT ,) (c) and (d) extrinsic semiconductors donor and acceptor levels in n-type and p-type semiconductors respectively are shown, (e) compensated semiconductor (f) metal (g) semimetal top of the valence band lies above the bottom of the conduction band. Figure 6.1 Schematic band structures of solids (a) insulator (kT ,) (b) intrinsic semiconductor (kT ,) (c) and (d) extrinsic semiconductors donor and acceptor levels in n-type and p-type semiconductors respectively are shown, (e) compensated semiconductor (f) metal (g) semimetal top of the valence band lies above the bottom of the conduction band.
The accessible deepness of donor centers extraction remains to be relatively small (probably, no more than several oxide lattice constants) because of its limitation by the low diffusion of oxygen, which is necessary for the oxidation of donor centers. To explain the experimentally observed appearance of a rather small concentration of relatively big Ag particles on the Ti02 electrodes, account must be given to the possibility of the lateral electron transfer from the neighboring donor centers, that is the electrochemical mechanism being of widespread occurrence in the processes of the chemical deposition of metals. In any case, metal nanoparticles deposited via the interaction of semiconductor donor centers with soluble metal ions prove to be localized at the sites of the electrode surface exposure of donor centers including continuous donor clusters. [Pg.178]

A bulk heteroj unction is by definition a blend of p-type and n-type semiconductors (donor/acceptor). As a prototype bulk heteroj unction, we shall discuss the properties of polymer/fullerene blends. Apart from the poly-... [Pg.166]

Figure 23. Theoretical space charge capacitance according to Bohnenkamp and Engell as a function of the voltage drop over the boundary - ( i - for intrinsic and doped semiconductors (donor... Figure 23. Theoretical space charge capacitance according to Bohnenkamp and Engell as a function of the voltage drop over the boundary - ( i - for intrinsic and doped semiconductors (donor...
In group-IV semiconductors, donors like P and As and acceptors like Al are monoisotopic, but others show an isotopic distribution (see appendix D). Beyond EMT, calculations of the isotopic splitting of the ground state of... [Pg.163]

A structural correlation of the AR rectifier to a normal silicon junction diode shows that, acceptor part of the molecule can be mimicked with p-type semiconductor, donor part can be mimicked with n-type semiconductor and o-bond can mimic the pn-j unction barrier. With these favorable structural features of an organic molecule, it can be expected to result in similar characteristics like that of a semiconductor rectifier. [Pg.102]

In an extrinsic semiconductor, tlie conductivity is dominated by tlie e (or h ) in tlie CB (or VB) provided by shallow donors (or acceptors). If tlie dominant charge carriers are negative (electrons), tlie material is called n type. If tlie conduction is dominated by holes (positive charge carriers), tlie material is called p type. [Pg.2877]

All teclmologically important properties of semiconductors are detennined by defect-associated energy levels in the gap. The conductivity of pure semiconductors varies as g expf-A CgT), where is the gap. In most semiconductors with practical applications, the size of the gap, E 1-2 eV, makes the thennal excitation of electrons across the gap a relatively unimportant process. The introduction of shallow states into the gap through doping, with either donors or acceptors, allows for large changes in conductivity (figure C2.16.1). The donor and acceptor levels are typically a few meV below the CB and a few tens of meV above the VB, respectively. The depth of these levels usually scales with the size of the gap (see below). [Pg.2882]

Table 1. Common Donor and Acceptor Molecules Used in Organic Semiconductor and Devices... Table 1. Common Donor and Acceptor Molecules Used in Organic Semiconductor and Devices...
Selenium is an essential element and is beneficial at low concentrations, serving as an antioxidant. Lack of selenium affects thyroid function, and selenium deficiencies have been linked to Keshan Disease (34). Selenium at high levels, however, is toxic. Hydrogen selenide (which is used in semiconductor manufacturing) is extremely toxic, affecting the mucous membranes and respiratory system. However, the toxicity of most organ oselenium compounds used as donor compounds for organic semiconductors is not weU studied. [Pg.242]

Fig. 1. Band-edge energy diagram where the energy of electrons is higher in the conduction band than in the valence band (a) an undoped semiconductor having a thermally excited carrier (b) n-ty e doped semiconductor having shallow donors and (c) a -type doped semiconductor having shallow acceptors. Fig. 1. Band-edge energy diagram where the energy of electrons is higher in the conduction band than in the valence band (a) an undoped semiconductor having a thermally excited carrier (b) n-ty e doped semiconductor having shallow donors and (c) a -type doped semiconductor having shallow acceptors.
The impurity atoms used to form the p—n junction form well-defined energy levels within the band gap. These levels are shallow in the sense that the donor levels He close to the conduction band (Fig. lb) and the acceptor levels are close to the valence band (Fig. Ic). The thermal energy at room temperature is large enough for most of the dopant atoms contributing to the impurity levels to become ionized. Thus, in the -type region, some electrons in the valence band have sufficient thermal energy to be excited into the acceptor level and leave mobile holes in the valence band. Similar excitation occurs for electrons from the donor to conduction bands of the n-ty e material. The electrons in the conduction band of the n-ty e semiconductor and the holes in the valence band of the -type semiconductor are called majority carriers. Likewise, holes in the -type, and electrons in the -type semiconductor are called minority carriers. [Pg.126]

Fig. 2. Representation of the band edges in a semiconductor p—n junction where shallow donor, acceptor energies, and the Fermi level are labeled Ejy E, and E respectively, (a) Without external bias is the built-in potential of the p—n junction (b) under an appHed forward voltage F. ... Fig. 2. Representation of the band edges in a semiconductor p—n junction where shallow donor, acceptor energies, and the Fermi level are labeled Ejy E, and E respectively, (a) Without external bias is the built-in potential of the p—n junction (b) under an appHed forward voltage F. ...
Fig. 1. Photoexcitation modes iu a semiconductor having band gap energy, E, and impurity states, E. The photon energy must be sufficient to release an electron (° ) iato the conduction band (CB) or a hole (o) iato the valence band (VB) (a) an intrinsic detector (b) and (c) extrinsic donor and acceptor... Fig. 1. Photoexcitation modes iu a semiconductor having band gap energy, E, and impurity states, E. The photon energy must be sufficient to release an electron (° ) iato the conduction band (CB) or a hole (o) iato the valence band (VB) (a) an intrinsic detector (b) and (c) extrinsic donor and acceptor...
Impurity-produced plasmas in semiconductors do not have to be compensated by charges of the opposite sign. These plasmas can be produced by introduction of either electron donors or electron scavengers, ie, hole producers, into semiconductor lattices. Thek densities range from a lower limit set by the abihty to produce pure crystals particles/cm ) to values in excess of 10 particles/cm. Plasmas in semiconductors generally are dilute, so that... [Pg.114]

Electron Level Position. One essential condition of spectral sensitization by electron transfer is that the LUMO of the dye be positioned above the bottom of the conduction band, eg, > —3.23 eV in AgBr or > —4.25 eV in ZnO (108). To provide the desired frontier level position respectively to the valence and conduction bands of the semiconductor, it is necessary to use a polymethine with suitable electron-donor abiHty (Pq. Increasing the parameter (Pq leads to the frontier level shift up, and vice versa. Chain lengthening is known to be accompanied by a decrease of LUMO energy and hence by a decrease of sensitization properties. As a result, it is necessary to use dyes with high electron-donor abiHty for sensitization in the near-ir. The desired value of (Pq can be provided by end groups with the needed topological index Oq or suitable substituents (112). [Pg.499]

The carrier concentrations in doped or extrinsic semiconductors to which donor or acceptor atoms have been added can be deterrnined by considering the chemical kinetics or mass action of reactions between electrons and donor ions or between holes and acceptor ions. The condition for electrical neutraHty is given by equation 6. When the predominant dopants are donors, the semiconductor is... [Pg.345]

For lightly doped n-type semiconductors at normal operating temperatures there is complete donor dissociation (donor saturation). [Pg.345]

Strontium titanate [12060-59-2] SrTiO, becomes an n-ty e semiconductor when additional electrons are created on the Ti lattice sites by donor doping or when oxygen is removed from the material through heat treatment in a reducing atmosphere. The mobiUty of the electrons in the conduction band is about 6 crc] j(V-s). On the other hand, when ZnO is reduced, 2inc interstitials are formed and these act as donors, each yielding a free electron. [Pg.358]


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See also in sourсe #XX -- [ Pg.326 ]




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Donors semiconductor sensors

Extrinsic semiconductor donors

Metal Nanoparticles with the Associates of Donor Defects in Wide-Band-Gap n-type Semiconductors

Semiconductors donor states

Semiconductors donor type

Shallow Donors in Multi-Valley Semiconductors

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