Suppose a pure Si crystal has `5 xx 10^(22)` atoms `m^(-3)` . It is doped by 1 ppm concentration of pentavalent . As . Calculate the number of electrons and holes . Given that `n_(i) = 1.5 xx 10^(16) m^-3` .

Explanation

The thermally generated electrons (`n_(i) ~ 10^(16) m^(-3)`) are negligibly small as compared to those produced by doping .
Therefore , `n_(e) ~~ N_(D) ` . Since `n_(e) n_(h) = n_(i)^(2)` , the number of holes `n_(h) = (2.25 xx 10^(32))// (5 xx 10^(22))`
` ~ 4.5 xx 10^(9) m^(-3)`