Donors are elements added in the doping process that has one extra electron in the valence shell compared to the base or substrate semiconductor material. With this extra electron, there is no place in the semiconductor lattice for this electron, so it is either not connected or very loosely connected to the donor atom, so that atom “donates” an electron to the conduction band. This creates an n-type semiconductor material.
Donors are pentavalent impurity atoms that give up an electron. They are added during the doping process to create a n-type semiconductor.
Electronic Devices : Conventional Current Version, 9th Edition by Thomas L. Floyd
Diffused impurities with five valence electrons are called donor atoms.
Electronic Devices and Circuit Theory, 11th Edition by Robert L. Boylestad & Louis Nashelsky