DEFECT FORMATION IN ZNSE BOMBARDED BY ALPHA-PARTICLES

Defect formation in low-resistivity n-ZnSe single crystals has been st udied by deep-level transient capacitance spectroscopy. The donor conc entration in the crystals was N(D) = 2.9 x 10(17) cm-3. The samples we re, bombarded by an uncollimated beam of a particles from a Po-210 sou rce (4.5-5.3 MeV) with a flux density of 2 X 10(8) cm-2.s-1. Electron trapping centers with energies of 0.27 and 0.30 eV, due to thermal def ects, were found in the original crystals. The bombardment introduces electron trapping centers with energies of 0.27, 0.30, 0.40, and 0.7-0 .9 eV. It also introduces a series of hole trapping centers with energ ies of 0.3-0.7 eV. For the electron traps with an energy of 0.30 eV, t he dose dependence of the concentration is linear with a formation rat e of 1800 cm-1. The changes caused in the basic properties of Ag-ZnSe diodes by the bombardment (an increase in the barrier height, a decrea se in the capacitance, and an increase in the series resistance) resul t from the formation of a compensated surface layer of the semiconduct or with a conductivity close to the intrinsic value. This effect is ca used by the high formation rate of acceptor defects (zinc vacancies an d complexes containing them) during the bombardment and their compensa tion by shallow donors.