Concentration of the majority carrier

The threshold potential VT is defined as the point where inversion starts. For this point it is ([>s - 2 VF, because the inverted surface has to have the same concentration of minority carriers as the concentration of the majority carriers had before... 

Easily measurable, the capacity of a semiconducting electrode provides direct information about the space-charge layer. Figure 3.56 shows the experimental values for the capacitance of a ZnO electrode, an n-type semiconductor [21], The data are presented in the form of a Mott-Schottky diagram. From the slope of the straight line, the concentration of the majority carriers can be determined. In this case, we have... 

In the case of negative bias, the Fermi level moves closer to the valence band edge. Consequently, the concentration of the majority of carriers (holes) at die insulator-semiconductor interface becomes laiger than in the bulk. This corresponds to the accumulation regime. When a positive bias is applied to die metal, the... 

Ti. This leads to an increase in the concentration of the majority (electron) carriers and therefore the conductivity. The photocurrent densities sometimes vary due to incomplete dissolution as well as large dopant concentrations [10]. Raising the sintering temperature of Ti02 Nb to 1350°C and maintaining the doping concentration ND/[Ti j in the range of 0.05 at%, leads to an increase in photocurrent by a factor three [11]. 

In the Seebeck or thermoelectric effect a voltage difference arises between two contacts to a semiconductor when they are held at different temperatures. Results are usually expressed in terms of the Seebeck coefficient, the ratio of the voltage difference to the temperature difference. The polarity of the thermoelectric power determines the sign of the majority carrier as the polarity of the cold junction. CompUcations (and incorrect interpretations) may arise if the space charge layers are too thick or the carrier concentration too low. The technique does not distinguish between electronic and ionic conduction. 

For clarification of the type of junctions formed at the semiconductor-electrolyte, let us take an example of n-type semiconductor. In addition to possessing free electrons (referred to as the majority carrier), n-type semiconductor also possesses holes (referred to as the minority carrier). The concentration of holes is temperature-dependent and is equivalent to the intrinsic concentration of the carrier (which is related to the concentration of Frankel defects). It can be shown mathematically that the Fermi level of minority carrier hes at almost half the band gap position. On the other hand, the concentration of majority carriers as well as the Fermi level depends on doping concentration. Thus, the Fermi level of the majority carrier can he anywhere between the conduction hand edge and the intrinsic Fermi level that is situated at i g. 

The limit of concentration decrease of the majority carriers in the exclusion case is dopant concentration. In order to preserve electroneutrality, the concentration of minority carrier decreases several orders of magnitude more. The result is an intensive carrier depletion near the top surface and thus Auger suppression. 

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