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Some Features of the Transport of Charge Carriers in the Grain Boundaries of Polycrystalline Silicon
| Content Provider | Semantic Scholar |
|---|---|
| Author | Olimov, L. O. Abdurakhmanov, B. M. |
| Copyright Year | 2014 |
| Abstract | We propose and discuss the mechanism of charge transport in polycrystalline silicon wafers with a thickness comparable to the grain size. Determining influence on the transport processes of the carriers during heating of the samples have deep energy levels caused by grain boundaries, and thermal generated carriers as a result of interaction with the recombination centers do not recombine, and are involved in the conduction proposed in the article, the mechanism. In [1,2], where the transport of charge carriers (СС) in the heated polycrystalline semiconductor structures in terms of their interaction with recombination centers associated with deep impurity states in the grain boundaries (GB) was found an abrupt change in the mobility and carrier concentration, which occurs in the temperature range 300÷800 K. as a result, the total concentration of CC, as it turns out, is determined by the concentration of CC trapped recombination centers (RC) caused by impurity states and defects in the GB, the total size of the combined layer which two adjacent grains of the polycrystalline silicon (PS) according to [3] is within ~ 7 nm. Sequential expression of RC at the sample is heated PS energy levels, for example, E~0.15 eV, E~0.17 eV, E~0.3 eV and E~0.36 eV, which is accompanied by an increase in the concentration of CC trapped at these levels, with the total concentration of CC is reduced [1, 2], and the conductivity of GB in the PS material increases [3], and, conversely, a decrease in the carrier concentration captured RC leads to an increase in the total concentration of CC [1 , 2], but is accompanied by a reduction in the conductivity of GB [3]. Furthermore, during an abrupt change in the concentration of CC takes place switching current and voltage measured in the heated samples, that is, change in direction of motion of the CC, which occurs in the temperature range of [3], within the areas of GB, that is in quantities of nano-metric sizes. Note that the motion of CC in such amounts may be accompanied by quantum size effects. This work is similar to [1-6] is also devoted to the analysis of the mechanism of charge transport in the area of the GB, ie, process drift of CC at the RC when the sample is heated PS, but contains two innovations. The novelty lies in bringing to explain the processes of transport of CC in the GB (Figure 1a), the thermionic emission model [4] and is selected as the object of study of PS wafers with a thickness comparable to the grain size. Since the samples are selected for the study of PS wafers of p-type conductivity, a thickness of 200 microns and a grain size ~250 microns. The simplified circuit samples embodiment with the contacts on the edges and the planes are shown respectively in Figures 1b and 1d. A figure 1c and 1e shows the equivalent electrical circuit of these options. From Figure 1 it follows that the CC in these samples have transitions of two types, namely, the transition of CC from one grain to another (Figure 1b), and along the GB (ris.1d). |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.arcjournals.org/pdfs/ijarps/v1-i6/2.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
