what are the properties of polymers and semiconductors?

in case of semiconductors.
Variable conductivity
Semiconductors in their natural state are poor conductors because acurrentrequires the flow of electrons, and semiconductors have theirvalence bandsfilled. There are several developed techniques that allows semiconducting materials to behave like conducting materials, such asdopingorgating.
Heterojunctions
Heterojunctions occur when two differently doped semiconducting materials are joined together. For example, a configuration could consist of p-doped and n-dopedgermanium. This results in an exchange of electrons and holes between the differently doped semiconducting materials.
Excited Electrons
A difference in electric potential on a semiconducting material would cause it to leave thermal equilibrium and create a non-equilibrium situation. This introduces electrons and holes to the system, which interact via a process calledambipolar diffusion.
Light emission
In certain semiconductors, excited electrons can relax by emitting light instead of producing heat. These semiconductors are used in the construction oflight emitting diodesand fluorescentquantum dots.
Thermal energy conversion
Semiconductors have largethermoelectric power factorsmaking them useful inthermoelectric generators, as well as highthermoelectric figures of meritmaking them useful inthermoelectric coolers.