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.

2 answers

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.