At very low temperatures the carrier concentration in one of these materials appears to diminish very rapidly. Why is this?
Please choose the option that BEST describes this phenomenon.
the dopant can no larger ionize
What about the a? The graph below shows two conductivity curves with respect to temperature of a germanium semiconductor. In one case, there is dopant added to the sample, and in the other there is none. Using some or all of the labels below, please drag and drop the labels to their correct destination to identify each curve and the appropriate regions.
The phenomenon described here is known as the decrease in carrier concentration at very low temperatures. To understand why this happens, we need to consider the concept of carrier generation and thermal excitation.
At higher temperatures, thermal energy provides enough energy for electrons to overcome the energy barriers and move from the valence band to the conduction band, resulting in the generation of charge carriers (electrons or holes). These carriers contribute to the total carrier concentration in the material.
However, at very low temperatures, thermal excitation decreases significantly. The reduced thermal energy makes it more difficult for electrons to gain enough energy to jump the energy bandgap and transition from the valence band to the conduction band. As a result, the generation of new carriers decreases, leading to a diminished carrier concentration.
In summary, the decrease in carrier concentration at very low temperatures occurs due to the reduced thermal excitation, which limits the generation of new charge carriers in the material.