What is intrinsic scmicondoctor?

Answer 1

A completely pure semiconductor crystal is called intrinsic, to underline that no substance is inserted in the crystal as impurity. An intrinsic semiconductor has a very low conductivity (it is almost an insulator, even if a current can flow if it undergoes a great voltage difference. Selected intrinsic semiconductors like Indium Phosphate (InP) or Gallium Arsenide (GaAs) are instead very effective in creating photo-stimulated electrical current (that is electrical current due to absorption of incident light) at a specific frequency called resonance frequency of the semiconductor. Other semiconductors (like Silicon, Si) lack this capability. This difference is related to the quantum mechanical behaviour of electrons in the different crystals.

A semiconductor crystal where selected substances called dopants (like phosphorous or arsenic) are inserted in the crystal to give it particular properties is called doped semiconductor.

Doping is more frequently used to create free charges in the semiconductor and increase conductivity. Depending on the sign of the virtual particle generated by doping in the crystal the doped semiconductor is called p doped (positive carrier generated) or n doped (negative carrier generated).