why does the conductance of semiconductor increase with increase in temperature?

Conductance depends on no. of free electrons as we increase temperature in semicondutor no. of free electrons increase resulting in increase in conductivity.

when we heat a semiconductor , the heat energy is absorbed by the free electrons and the electrons in the outermost shells of the atoms. the free electron move more easily and the electrons in outermost shells are easily detached from the atoms and in this way the no. of free electrons in incresed.so the conductivity increases.