Physics Talk

Guillom assumed (based on copyright claims): https://commons.wikimedia.org/wiki/File:N-doped_Si.svg In Part 1 ( https://phys-talk.blogspot.com/2020/07/semiconductors-part-1-introduction-band.html ), we looked at the basics of semiconductors, using band theory to visualise how they differ from insulators and conductors. From Part 1, we learned that silicon is classed as a semiconductor due to the small energy gap between the valence and conduction bands. However, the conductivity of pure silicon is low and therefore it is not very useful in electronics. Doping is a method implemented to alter the properties of a semiconductor and modify its conductivity. It involves adding impurities to an intrinsic semiconductor (like silicon) to ‘generate either a surplus or a deficiency in valence electrons.’ [1] This imbalance allows for the movement of electrons through the material and therefore current can flow. N-type semiconductors This diagram shows the structure of doped Silic...

  zathris (pixabay user):  https://pixabay.com/photos/cpu-chip-semiconductor-condenser-3061923/ Intrinsic to modern electronics, semiconductors are defined as ‘crystalline solids intermediate in electrical conductivity between a conductor and an insulator.’ [1] They have been incorporated in numerous devices including computers, smartphones, bank ATM’s, televisions, washing machines, trains and LED bulbs just to name a few. [2] Band theory Band theory is helpful in visualising the difference between conductors, semiconductors and insulators. Quantum physics dictates that for isolated atoms, the energy states that electrons can occupy are quantised. However, when atoms are brought together to make solids, ‘these discrete energy levels become perturbed through quantum mechanical effects’ [3] As a result, the electrons can occupy a range of energies within a certain energy band. The electrons in an atoms outer shell are situated in an energy band called the valence band. M...