Doping in Semiconductors

Doping is the process of intentionally introducing impurities into a pure semiconductor material to modify its electrical properties. The impurities are classified into two types; donors (n-type) and acceptors (p-type). Donor impurities are atoms that offer extra electrons to the semiconductor crystal, while acceptor impurities are atoms that offer holes or vacant spaces in the crystal structure.

Heavy Doping

Heavy doping refers to the process of increasing the impurity concentration in a semiconductor material beyond a certain limit. The limit is determined by the doping concentration that produces a maximum number of free charge carriers in the material without causing excessive recombination or breakdown. Heavy doping is mostly used to create highly conductive p and n-type semiconductors for electronic devices such as diodes, transistors, and solar cells.

Impurity Concentration

Impurity concentration is the measure of the number of impurity atoms introduced into a pure semiconductor material. It is usually expressed as the ratio of the number of impurity atoms to the total number of semiconductor atoms. The concentration is determined by the doping process, which can be achieved through diffusion, ion implantation, or epitaxy.

Answer

The correct answer is d) 103. Heavy doping of a semiconductor corresponds to impurity concentration of 1 part in 1000. This means that for every 1000 semiconductor atoms, one impurity atom is introduced. The concentration is represented in scientific notation as 1x10^3 or 0.1%.