The product of the hole concentration and the conduction electron concentration turns out to be independent of the amount of any impurity doped. The concentration of conduction electrons in germanium is `6xx10^19`per cubic per cubic metre.When some phosphorus impurity is doped into a germanium sample, the concentration of conduction electrons increases to `2xx10^28`per cubic metre.Find the concentration of the holes in the doped germanium.

Explanation

(Number of holes)
(Number of condution electrons) = Constant
Number of condution electrons
`= 6xx10^19`
number of holes` = 6xx10^19`
After doping.
Number of condition electrons
` = 2xx10^19`
number of holes `=x`
`(6xx10^19) (6xx10^19) = (2xx10^23)x`
`(6xx6xx10^(19+19))/(2xx10^23) =x`
`x = 18xx10^(15) = 1.8xx10^16`