(2) p-type doping: In this, element with three valence electron are added as impurity (trivalent impurity or acceptor impurity) in the semiconductor. The three electron in the semiconductor bonds with the three electrons of the dopant. The one electron could not make bond and thus the vacant space where electron should be there is created. This vacant space is know as holes. Electron from another atom jumps in these hole to fill it and a hole is created there, and then the same thing continues. Thus, by this way conductivity is  increased in p-type doping.