following transfer, the diffused electrons come into contact with holes and are eliminated by recombination in the p-side. likewise, the diffused holes are recombined with free electrons so eliminated in the n-side. the net result is that the diffused electrons and holes are gone. in a n-side region near to the junction interface, free electrons in the conduction band are gone due to (1) the diffusion of electrons to the p-side and (2) recombination of electrons to holes that are diffused from the p-side. holes in a p-side region near to the interface are also gone by a similar reason. as a result, majority charge carriers (free electrons for the n-type semiconductor, and holes for the p-type semiconductor) are depleted in the region around the junction interface, so this region is called the depletion region or depletion zone. due to the majority charge carrier diffusion described above, the depletion region is charged; the n-side of it is positively charged and the p-side of it is negatively charged. this creates an electric field that provides a force opposing the charge diffusion. when the electric field is sufficiently strong to cease further diffusion of holes and electrons, the depletion region reached the equilibrium. integrating the electric field across the depletion region determines what is called the built-in voltage (also called the junction voltage or barrier voltage or contact potential).