Semiconductors acceptor type

It was shown in [98] that during acceptor adsorption in a broad band semiconductor of -type characterized by availability of an a priori surface-adjacent depletion zone developing depletion of BSS levels slows... 

By varying the impurity concentration in the semiconductor, one may regulate not only the activity of the catalyst but its selectivity as well. Indeed, if the reaction proceeds along two parallel paths, one of which is of the acceptor type and the other of the donor type, then upon the monotonic displacement of the Fermi level (i.e., upon the monotonic change of Z) the reaction will be accelerated on one path and retarded on the other, as appears, e.g., from a comparison of Figs. 19a and 19b. Doping of the crystal may accelerate the reaction on one path and retard it on the other. 

Polymeric solar cells with a bandgap > 2 eV are spectrally so badly mismatched to the solar spectrum that their efficiency is severely restricted. It is essential to develop polymeric semiconductors with lower bandgap. Low bandgap polymeric semiconductors behave similarly in conjunction with fullerenes as n-type semiconductors (acceptors). 

In intrinsic semiconductors, considerable effects are possible, provided that the concentration of charge carriers remains small in comparison with the values of 10 and 10 just cited. Depending on whether the donor or acceptor type of defect is predominant, transformation may result into n- or p-type extrinsic semiconductor. 

Define the following terms conductor, insulator, semiconducting elements, donor impurities, acceptor impurities, w-type semiconductors, p-type semiconductors. 

In the simplest case, a p-n junction is formed between two layers of the same semiconductor with different types of dopants, creating a p-n homojunction. One semiconductor contains dopants that are acceptor-type (p-type), making it a semiconductor with a Fermi level lower than the intrinsic, or undoped, semiconductor. The other contains donor-type (n-type) dopants, making it a semiconductor with a Fermi level higher than that of the intrinsic material. When the n-type and p-type semiconductor layers are brought into contact, there is a discontinuity in the Fermi level at the interface between the two materials, and charge will flow across this interface until... 

Conversely, acceptor-type impurities induce a rise in positive hole concentration in the valence band. The Fermi level goes down and approaches the top of the valence band this is for a semiconductor of type p, such that p > n (see Figure 3.7c). 

Figure 4.1. Semiconductor with surface states of acceptor-type (a, b) or donor-type (c, d)...

If we suppose that there is, in the semiconductor, an acceptor-type impurity A as well as a donor-type impurity D, that their concentrations at charged state are respectively N and N+, and that the charge density p(x) is written ... 

Figures 4.5a and 4.5b represent the bands of a semiconductor n in the presence of electron acceptor-type molecules at the beginning of adsorption and at adsorption equihbrium.

For a semiconductor containing both a singly-ionized donor-type impurity D, of concentration Nd, as well as a singly-ionized acceptor-type impurity A, of concentration Na, the density p(V) can be expressed using relation [4.7] ... 

With the development of organic semicondnctors which support electron or hole transport (in analogy of p- and n-type inorganic semiconductors) bilayer type p-n heterojunction devices have been constructed. In the case when organic p- and n-type materials are deposited consecutively in two layers we get lateral heterojunction devices which mimic classical p-n junction junction solar cells based on silicon. The first such cell was designed by Tang and pnb-lished in 1986 (Fignre 3)." Copper phthalocyanine was utilized as electron donor (p-type) material, whereas pery-lene derivative was nsed as electron acceptor connterpart (n-type material). 

In Eq. (1), the short-circuit current (/ ) is the maximum current that can run through the cell. The open circuit voltage (E depends on the highest occupied molecular orbital (homo)level of the donor (p-type semiconductor quasi Fermi level) and the lowest unoccupied molecular orbital(lumo) level of the acceptor ( -type semiconductor quasi Fermi level), linearly. 

The analysis given applies whether or not there is an insulating layer, and can be used to study the effect of it on the electrostatic regime. Consider first the n-type case. Photogeneration of carriers causes the electron Fermi level to rise in the semiconductor, and more acceptor-type surface states are able to capture electrons from the semiconductor. The semiconductor space charge density P (x), now no longer considered to be x-independent,... 

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