STATE OF DOPANT NICKEL IN CADMIUM TELLURIDE

A study has been made of the spectra of the impurity absorption and th e photovoltaic current of CdTe crystals doped with nickel in the conce ntration range 10(18)-5 X 10(19) cm-3. It is found that the nickel is in two charge states: Ni2+ (3d8) and Ni+ (3d9). The energies found for the donor and acceptor states from the spectra of the photovoltaic cu rrent and the Hall effect are in reasonable agreement. However, the de ep levels found cannot be assigned to pure impurity states. Since the susceptibility of CdTe:Ni crystals does not have a paramagnetic compon ent, and since the compensation of free carriers is pronounced (n cong ruent-to p almost-equal-to 10(7)-10(8) cm-3 at T = 300 K), it is concl uded that neutral complexes form. The depth of these complexes has bee n determined.