Sensitization is an important engineering procedure to amplify the response of photoconductive materials. The photoconductive gain is proportional to the lifetime of photo-excited carriers (either electrons or holes). Sensitization involves intentional impurity doping that saturates native recombination centers with a short characteristic lifetime, and replacing these centers with new recombination centers having a longer lifetime. This procedure, when done correctly, results in an increase in the photoconductive gain of several orders of magnitude and is used in the production of commercial photoconductive devices. The text by Albert Rose is the work of reference for sensitization.