Suppose an intrinsic semiconductor has 1 billion free electrons at room temperature (25°C). If the temperature changes to 75°C, how many holes are there?
Right Answer is:
When heat energy creates an electron, it automatically creates a hole at the same time. Therefore, in an intrinsic semiconductor crystal always has the same number of holes and free electrons. if there are 1 billion free electrons, there are 1 billion holes.
Higher temperature increases the vibrations at the atomic level, which means that more free electrons and holes are created. But no matter what the temperature is, a pure intrinsic semiconductor has the same number of free electrons and holes.