Room-temperature electron irradiation of n-type InP

Crystals of n-type doped InP were irradiated with 3 MeV electrons at 150C. The Hall coefficient was measured from 20 to 300 K before and after each electron dose. Irradiation is found to give rise to a decrease of the carrier concentration n0 and an increase of the slope of the curve n0(T) at high temperature, with increasing integrated flux phi, emphasizing the introduction of deep donor centres. The fit of the n0(T) curves for different flux phi indicates the existence of two donor levels, one at 130 meV and a second deeper one lying within 300 to 400 meV below the conduction band. The formation of the deeper donor centres was discussed as a function of the impurity concentration and of the flux. On the other hand, evidence for the introduction of the deeper donor level was observed at 3000 cm-1 in preliminary optical absorption results at 10 K. (author)