The electrical properties of deep copper- and nickel-related centers in silicon

Abstract

The dominant deep level defects related to copper and nickel in p-type silicon have been studied using deep level transient spectroscopy. Three acceptor states are observed in copper-doped silicon (Ev+0.20 eV, Ev+0.35 eV, and Ev+0.53 eV) and three acceptor states observed in nickel-doped silicon (Ev+0.18 eV, Ev+0.21 eV, and Ev+0.33 eV). All of these defects are neutralized by reaction with atomic hydrogen, and a concentration profile for the Ev+0.18 eV Ni-related state is given as a function of the duration and temperature of the exposure to the hydrogen plasma. Gamma irradiation produces additional donor levels at Ec−0.38 eV in the copper-doped material, and at Ec−0.32 eV in the nickel-doped material. Finally, the room temperature motion of three of the acceptor levels, Cu(Ev+0.20 eV) and Ni(Ev+0.21 eV, Ev+0.33 eV), under the influence of the electric field in a reverse biased p-n junction is reported. The mobilities obtained for centers associated with these three levels at 25 °C were 10−14, 6×10−15, and 2×10−15 cm2 V−1 s−1, respectively.