Hole lifetime

The lesponsivity becomes independent of the bias voltage, V when the electric field-induced sweep time of the holes equals the hole lifetime. 

The above mechanism suggests that the presence of adsorbed oxygen 02(ads) is essential for photocatalysis. It allows an increase of hole lifetime by reaction with an electron and the formation of oxidizing OH radicals. 

Core hole, 34 210 core-hole lifetime, 34 215 Core level shift, C(ls), 29 13-14 Core-state excitation, 34 204 Correlation data, structure effects, 29 159-160 Correlations, adsorptivity, 29 189-190 Co9Sg, structure, 40 222 CoSiOj powders, Fischer-Tropsch synthesis, 39 288-289... 

The space charge region is denoted by length w, while Lp is the hole (minority carrier) diffusion length. Zp is the minority carrier (hole) lifetime, jp the (minority carrier) hole mobility, and Dp the minority carrier diffusion coefficient. 

The same article first critically reviewed the IFTOF principle with its various distinct advantages and then applied the technique to the measurement of the spatial dependence of the hole lifetimes in Cl-doped amorphous Se 0.3%As X-ray plates used in X-ray imaging. The hole lifetime could be measured as a function of location in the term, and the changes in the spatial variation of the lifetime conld be determined upon exposnre to X-rays. The IFTOF technique is shown to be an extremely powerful tool for studying spatial dependence of charge transport and trapping parameters in the sample. 

Here Dp is the hole diffusion coefficient and Lp = (Dptp)112 is the diffusion length, where tp is the hole lifetime. This expression for ijjm coincides with a known formula (see, for instance, Middlebroock, 1957) for the saturation current of a p- junction. 

T.X. Carroll, N. Berrah, J. Bozek, J. Hahne, E. Kukk, L.J. Saethre, T.D. Thomas, Carbon Is photoelectron spectrum of methane Vibrational excitation and core-hole lifetime, Phys. Rev. A 59 (1999) 3386. 

The lifetime of the simplest quasiparticle, i.e. a hole in a surface band, can be obtained experimentally from the width of the corresponding peak in ARPES, since the spectral linewidth of a quasiparticle excitation in the energy space is inversely related to its lifetime. The lower panel of Fig. 4 shows the widths of the photoemission peaks at normal emission corresponding to the L-gap surface states. It can be shown [45] that for a 2D band such as these, the widths reflect the initial state (hole) lifetime. For these surface states the lifetime ranges from 30 to 110 femtoseconds (ImeV corresponds to a lifetime of 0.67 x 10 12s). 

Enokida et al. (1991) measured hole mdbilities of PMPS before and after ultraviolet exposures. The exposures were of the order of 1 erg/s-cm2. Prior to the exposures, the mobilities were approximately 10-4 cm2/Vs and weakly field dependent. Following the exposures, a decrease in the mobility was observed. Under vacuum exposure conditions, a decrease of approximately 40% was observed for a 1 h exposure. Under atmospheric conditions, however, the decrease was approximately a factor of 4. Enokida et al. attributed the decrease in mobility to the formation of Si-O-Si bonds in the Si backbone chain. A similar study of PMPS was described by Naito et al. (1991). While the field and temperature dependencies of the mobility were not affected by the ultraviolet exposures, the dispersion in transit times increased significantly. The change in dispersion could be removed by subsequent annealing. The authors attributed the increase in transit time dispersion to a reduction in the hole lifetime, induced by Si dangling bonds created by the ultraviolet radiation. 

For second row transition metals, the corresponding Is 4d transition requires very high energies. Low monochromator resolution and short core-hole lifetimes hinder the ability to detect this transition in many cases. Other options to obtain information for these metals rely on intensity estimations of the 2p 4d (allowed) transitions at the f Cn.iii) edges. Another promising approach, mentioned in... 

Chiang, T. C., J. A. Knapp, M. Aono, and D. E. Eastman (1980). Angle-resolved photoemission, valence band dispersion, E(k) and electron hole lifetimes for GaAs. Phys. Rev. B21, 3513-22. 

The large lifetime broadening, due to the limited electron and hole lifetime at high excitation energies, places an upper limit on Z. 

In AgCl powders and emulsions prepared from solutions containing an excess of silver ions at the termination of precipitation, deep electron trapping impurities such as Ir3 + extend the hole lifetime to such an extent that stable Ag2 + centers can be formed by hole trapping at silver ions adsorbed at the... 

Values reported for (PdBr6)5 centers produced by dark annealing at 600 K (i.e., in the absence of holes). Lifetime <0.01 s when produced by light, suggesting a high recombination cross-section. 

The finite size of the cluster is determined by the mean free path for elastic scattering of the photoelectron as shown in Fig. 1 and by the core hole life time. In the energy range 1-10 eV, where the mean free path becomes longer than 10 A, the size limitation due to the core hole lifetime becomes the relevant one. The contribution of further shells can be cancelled by structural disorder as already discussed for transition metal ions in dilute solutions. 

Fig. 21. Palladium L,-XANES and K-XANES are compared with the calculated theoretical p(E) from the p-like partial density of states taking account of the matrix element of the Pd crystal before and after it has been smeared to account for lifetime effects. The difference between the L, and the K-edge is due to the better instrumental energy resolution in the energy range of the Lj edge and shorter core hole lifetime at the K-edge...

Fig. 22. L3 palladium edge of Pd metal (dotted line) compared with one-electron band theory (solid line) taking account of the partial (1 = 2) local density of states, of the inelastic mean free path and of the core-hole lifetime. The dashed line shows the total density of states of palladium metal, which is quite different from the absorption spectrum. The zero of the energy scale is fixed at the Fermi energy...

Here, Tp is the minority carrier (hole) lifetime. The difiusion coefficient for holes Dp is related to the microscopic mobility ftp by the Einstein relation Dp = (kTlq)pp. Here G x) is a generation function that describes the local disturbance. The solution to this diffusion equation is of the form... 

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