Minority carriers influence

A similar expression can be written for holes, which diffuse in the dark from the p to the n region and during illumination act as minority carriers from the n side to the space-charge region and move from there under the influence of the field into the p region ... 

Figure 16. Schematic of the influence of steps on diffusion processes in case d > > W. The lined areas indicate the extension of the depletion layer parallel or perpendicular to the layered structure, WM and W1, respectively, and I denotes the minority carrier diffusion length perpedicular to the layered structure (the horizontal radius of the ellipses is compressed somewhat).

In the absence of any trapping phenomenon, the data of Table XII must be compared to the carrier concentrations in the various types of solids in the absence of radiation. In intrinsic semiconductors, this concentration hardly exceeds 10 g. in very pure germanium, for instance, this value is equal to 2.5 X 10 . In extrinsic semiconductors the majority carrier concentration is generally between 10 and 10 g. the corresponding value for minority carriers is generally much lower and may be as small as 10 . Unless very high radiation intensities are used, it is thus seen that in the absence of trapping phenomenon, the influence of radiation upon the number of carriers can become appreciable only in the case of extrinsic semiconductors in other cases only the concentration of minority carriers is affected. 

Concerning extrinsic semiconductors, it has been seen in Section III,B,1 that in general none of the two types of defects exerts any observable influence upon the number of majority carriers. Consequently, appreciable catalytic effects are only hable to occur in those cases where the produced structural and electronic defects influence the number of minority carriers. It was noticed in that case that the character of the semiconductor may even be changed one may therefore expect important quahtative effects to occur in this way. 

Extrinsic semicondudars. In extrinsic semiconductors the number of majority carriers is very large, always exceeding largely 10 cm. . On the contrary, the very much smaller number of minority carriers can be influenced by irradiation to an appreciable extent their stationary concentration may in certain cases be multiplied by a factor of several powers of ten. The minority carriers which are thus produced may be at the origin of qualitative modifications of the catalytic activity. 

We have also seen that, although the lattice defects created by irradiation have a direct influence only upon the concentration of the minority carriers, they nevertheless are able to modify the n or p character of the semiconductor as well. This effect can only be observed in the case where the structure defects give rise to a greater number of minority carriers than those resulting from the pairs of excess carriers created by irradiation. 

The influence of deposited Pt nanopaiticles on the interfacial kinetics of silicon has been investigated by combining photocurrent and PMC measurements (Wiinsch et al, 1996). Sohd electrolyte contacts to sihcon have also been studied, and it has been found that the PMC signal follows the same potential dependence as with liquid electrolytes. It has been shown that by electropassivating the sihcon/electrolyte interface the bulk minority-carrier hfetime of silicon wafers can be determined from the PMC plateau in the accumulation region (Schulenberg and Tributsch, 2000). 

Although our results of calculation are rather qualitative one, Efimova eLal.[7] estimated the influence of the minority carriers on Z for n-type PbTe in more realistic fashion and indicated the minority carriers are responsible for a decrease of Z by 40-50% around T = 500-600. ... 

Semiconductor electrodes whose band gap is relatively narrow receive photon energy and produce photoexcited electron-hole pairs in the space charge layer. The photoexcited electron-hole pair formation significantly increases the concentration of minority charge carriers (holes in the n-type), but influences little the concentration of majority carriers (electrons in the n-type). The photoexcited electrons and holes set their energy levels not at the electrode Fermi level, ef, but at what we call the quasi-Fermi levels, n p and p p, respectively. The quasi-Fermi level for majority carriers is close to the electrode Fermi level, F, but the quasi-Fermi level for minority carriers is far away from the electrode Fermi level. 

F. A. Lindholm and J. G. Fossum, Pictorial derivation of the influence of degeneracy and disorder on nondegenerate minority-carrier concentration and recombination current in heavily doped silicon, IEEE Electron Device Lett. EDL-2 (1981) 230-234. 

Deep levels influence a variety of device parameters. For example, in minority carrier devices they influence the recombination and generation lifetimes. The lifetime in turn controls junction currents and refresh times in dynamic random access memories. For this reason we discuss lifetimes. Defects... 

Seeing this limitation, Jarrett proposed a revised model that allows for recombination in the space charge layer [8]. Jarrett considered the effects of low mobility on device efficiency by first examining the influence of mobility on the transit time, x the time required for minority carriers to cross the space charge layer. The transit time is calculated as... 

A thin slice of the semiconductor serves as the electrode, one side of which is contacted with another material to form a p-n-junction. If the distance between the surface of the slice used as electrode and the p-n-junction on the other side is in the order of the mean free path of the minority carriers, then injection or extraction of minority carriers through the p-n-junction diode will increase or reduce the supply of minority carriers for the electrode surface. This can clearly be seen in the influence of the diode voltage on the electrolytic current as shown in Fig. 23 for the case of a Germanium-electrode. Such a tool is very useful for quantitative measurements because the number of minority carriers reaching the electrode surface can be calculated and compared with the change of the electrolysis current. 

HENISCH No traps are needed to produce the relaxation regime in the sense AN < . When traps are present, the criterion for majority carrier depletion under the influence of minority carrier injections is no longer d/ o where Mg is the normalized... 

When the semiconductor-electrolyte junction is illuminated with light, photons having energies greater than the semiconductor band gap are absorbed and create electron-hole pairs in the semiconductor. Photons absorbed in the depletion layer produce electron-hole pairs that separate under the influence of the electric field present in the space charge region. Electron-hole pairs produced by absorption of photons beyond the depletion layer will separate if the minority carriers can diffuse to the depletion layer before recombination with the majority carriers occurs. 

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