A Si sample is doped with a fixed number of group N impurities. The electron density n is measured from 4 K to 1200 k for the sample. Which one of the following is correct?

• A. n remains constant over the temperature range
• B. n increases monotonicaliy with increasing temp
• C. n increases first remains constant over a range and again increases with increasing temperature
• D. n increases show a peak and then decrease with temperature