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Schottky barrier trapping

The rate of electron accumulation at ionized traps in the depletion zone of the Schottky barrier in the Au/ZnO contact is in proportion to the concentration of unoccupied traps, frequency of metal parti-cle/metastable atom interaction events, and to the probability of electron capture per a trap in a single event of interaction between metastable atoms and metal particle. [Pg.336]

Electric charge in surface states or ionic groups on the surface will particularly depend on imperfections found in the surface. Imperfections in the bulk will affect the extension of a Schottky barrier since such imperfections can form traps for electric charge. Such a case has been studied for example at zinc oxide (10). [Pg.4]

In many PEC systems the chemical kinetics for the primary charge transfer process at the interface are not observed at the light intensities of interest for practical devices and the interface can be modeled as a Schottky barrier. This is true because the inherent overpotential, the energy difference between where minority carriers are trapped at the band edge and the location of the appropriate redox potential in the electrolyte, drives the reaction of interest. The Schottky barrier assumption breaks down near zero bias where the effects of interface states or surface recombination become more important.(13)... [Pg.87]

This result is important since it shows that for finite (non-zero) Schottky barrier, i.e. P 0) < oo, and for large value of C, the current changes from the space charge limited current to the ohmic current. This result is similar to that given by Mott [36] for a trap-free insulator. Just before the ohmic region there is a transition region between the conventional power law and the ohmic region. [Pg.51]

Fig. 3.29(b) shows the published J-V curves of an Al/OCiCio/ITO diode by Jain et al. [40], [OCiCio is poly(2-methoxy-5-(3,7-dimethyloctyloxy)-p-phenylene vinylene).] In this paper [40] Jain et al. attributed the extremely fast rise of the hole current at low voltages to Shockley like current due to the forward biased Al Schottky contact. In their later paper [56] Jain et al. showed that by including the PFE they can fit the theory of bulk limited trap controlled space charge currents with the same experimental results (see Fig. 3.29(b)). Jain et al. [40] suggested that PFE induces the high injection effect earlier, which presumably makes the Schottky barrier at the Al contact small. [Pg.68]

As described above, the DLTS experiment consists basically of applying a forward bias to a normally reverse-biased Schottky barrier or p-n junction [8,9]. In reverse bias, more of the traps are in a region depleted of free electrons, and thus experience a very low free-electron concentration, n = nr <3C rib, where rib is the bulk (neutral) value, 1018 cm-3 in our case. Thus, c o(nr,T) is very small, so that emission dominates and the traps are almost empty. Then, in forward bias, the traps are suddenly exposed to the bulk free-electron concentration n = rib for a time tp, the filling... [Pg.236]

Most impurity and defect states in SiC can be considered as deep levels. Both capacitance and admittance spectroscopy provide data on these deep levels which can act as donor or acceptor traps. Bulk 6H-SiC contains intrinsic defects which are thermally stable, up to 1700 °C. In epitaxial films of 6H-SiC a deep acceptor level is seen in boron-implanted samples but not when other impurities are implanted. Other centres, acting as electron traps, are also seen in p-n junction and Schottky barrier structures. Irradiation of 6H-SiC produces 6 deep levels, reducing to 2 after annealing. Only limited studies have been carried out on the 3C-SiC polytype, in the form of epitaxial films on silicon substrates. No levels were seen in thick films but electron traps were seen in thin n-type films and a hole trap (structural defect) was found to be a mobility killer. Neutron irradiation produces defects most of which can be removed by annealing. Two levels were found in Al-implanted 4H-SiC. [Pg.97]

The ZnO grains are n-type semiconductors. The intergranular traps are formed in this grain boundary due to the presence of Bi203 or PriOs and transition metal oxides, which cause the double Schottky barrier. [Pg.34]

When a voltage V is applied across the double Schottky barrier, the barrier height (j) decreases with increase of the voltage. A small fraction of electrons can penetrate the depletion region. These electrons, which are accelerated in the depletion region, can excite the valence electrons to conduction band. Therefore, holes recombine with the trapped electrons at the grain boundary, and decrease the barrier height. [Pg.34]

For material with Kttle carrier trapping, the response time is determined by carrier lifetime. As device dimensions get smaller, however, the response time can be altered by the nature of the metal contact and the method of biasing. With nonaUoyed contacts to the MSM device, Schottky barriers can be formed at the metal semiconductor interfaces, and the depletion region extends across the length of the photoconductor. In this case, the device operates more or less like a photodiode with r replaced by t , and its MB value becomes 1/t (see Eq. (9.19)). [Pg.976]

Schematic voltage-current relationship for majority carrier injection into a material containii traps, in the absence of a Schottky barrier. [After Lampert and Mark( ).]... Schematic voltage-current relationship for majority carrier injection into a material containii traps, in the absence of a Schottky barrier. [After Lampert and Mark( ).]...
Fig. 10. Energy states for an insulating micro-region on a metal cathode under an applied field (after Latham, 1982). Electrons tunnel from cathode to conduction band of insulator through Schottky barrier, A. Electron traps become filled, B. Electrons accumulate at electron-affinity barrier at insulation-vacuum interface, C. Holes produced by collision ionization drift to A and enhance electron tunnelling. Electrons with enhanced kinetic energy emitted over barrier C into liquid conduction band, D. Positive hole states of liquid E, ... Fig. 10. Energy states for an insulating micro-region on a metal cathode under an applied field (after Latham, 1982). Electrons tunnel from cathode to conduction band of insulator through Schottky barrier, A. Electron traps become filled, B. Electrons accumulate at electron-affinity barrier at insulation-vacuum interface, C. Holes produced by collision ionization drift to A and enhance electron tunnelling. Electrons with enhanced kinetic energy emitted over barrier C into liquid conduction band, D. Positive hole states of liquid E, ...

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See also in sourсe #XX -- [ Pg.106 ]




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