Intrinsic bandgap

Various thiophene polymers have intrinsic bandgaps that cover a wide range. Table 7.1 shows a few typical examples and also demonstrates that calculations can reproduce the experimental data consistently... 

Ktirti and Surjan, 1990 Karpfen and Kertesz, 1991 Kiebooms et al 1995). Quinonoid polymers with intrinsic bandgaps significantly lower than 1 eV without doping have not yet been synthesized. 

Tian et al., 2008), while the gap of C2SHel is 4.10 eV (at the B3LYP/6-31G level). The 2.7 eV value indicates limited delocalization for the carbon skeleton alone and is the main reason why C2S helicene has a large intrinsic bandgap. 

Electron-phonon coupling shifts the intrinsic bandgap Eq to the EpA or the Epp by an addition or subtraction of the Stokes shift that also changes with solid size [23]. 

Experimental n T) data are a source of information about the material we can infer the intrinsic bandgap from the slope in the region D-E the impurity concentration from n in region C-D the impurity level from the slope in region B-C and the photon arrival rate from the carrier density n in region A-B. For detector operation, we want to work in a region where the carrier concentration is dominated by the photon arrival rate, not by thermal effects. To work at reduced backgrounds, will require that we work at lower temperatures - temperature B versus temperature 52 ... 

Semiconductors are materials that contain a relatively small number of current carriers compared to conductors such as metals. Intrinsic semiconductors are materials in which electrons can be excited across a forbidden zone (bandgap) so that there are carriers in both the valence (holes, p-type) and conduction (electrons, ra-type) bands. The crucial difference between a semiconductor and an insulator is the magnitude of the energy separation between the bands, called the bandgap (Eg). In the majority of useful semiconducting materials this is of the order of 1 eV some common semiconductors are listed in Table 1. 

In intrinsic semiconductors Av Ac, therefore EF lies approximately in the middle of the bandgap. For the intrinsic semiconductor, the concentration of holes and electrons is equal because they are generated by the same process. Therefore... 

There are three basic types of semiconductor materials depending on their ability to conduct hole (p-type), electrons (n-type), or both (ambipo-lar) under different gate bias conditions. In semiconductor materials, reduction of the bandgap (Eg) will enhance the thermal population of the conduction band and thus increase the number of intrinsic charge carriers. The decrease of Eg can led to true organic metals showing intrinsic electrical conductivity. 

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