Doping
The intentional alloying of semiconducting materials with controlled concentrations of donor or acceptor impurities
Dormancy
(F. dormir, from L. dormire the life of an animal or plant completely ceases.
Physiological changes associated with dormancy help the organism survive
adverse environmental conditions. Annual plants survive the winter as dormant
seeds, while many perennial plants survive as dormant tubers, rhizomes, or bulbs.
Hibernation and aestivation in animals help them survive extremes of cold and heat, respectively. cf rest period


