In an n-type semiconductor if n and p are the concentration of electrons and holes respectively and `n_(i)` is the concentration of electron-hole pairs in a pure semiconductor then

How are electron-hole pairs created in a semiconductor?

A hole in a P - type semiconductor is

In n-type semiconductors the electron concentration is equal to

A pure semiconductor germanium or silicon, free of every impurity is called intrinsic semiconductor. A room temperature, a pure semiconductor has a very small number of current carriers (electrons and holes). Hence, its conductivity is low. When the impurity atoms of valence five or three are doped in a pure semiconductor, we get repectively n-type ot p-type extrinsic semiconductor. In case of a doped semiconductor. n_(e)n_(h)=n_(i)^(2) , where n_(e) and n_(h) are the number density of electrons and holes respectively and n_(i) is the number density of intrinsic charge carriers in a pure semiconductor. The conductivity of extrinsic semiconductor is much higher than that of intrinsic semiconductor. (i) Name two materials to be doped in pure semiconductor of silicon to get p-type semiconductor n-type semiconductor. (ii) What do you learn from the above study?

How electron -hole pairs are created in a semiconductor material ?

Let n_(e) and n_(b) are the number density of electrons and holes in extrinsic semiconductor then-