Electrical and optical properties of SiO2 thin layers implanted with Zn ions

Abstract

This paper presents the results of electrical and optical measurements of 600 nm thick silicon dioxide on Si layers to which zinc ions have been implanted. Following ion implantation the samples were annealed in air at 1023 K for 2 h. For the samples immediately after preparation and being annealed, AC measurements of resistivity Rp, phase angle θ , capacity Cp, and dielectric loss factor tanθ were made as a function of frequency (measurement range 50 Hz-5 MHz) and the measurement temperature (20 K-375 K). On this basis, the frequency-temperature dependence of conductivity δ was prepared. The strong frequency dependence of conductivity indicates that in the Zn/SiO2 layer after annealing, the conductivity takes place by hopping exchange (tunneling) of electrons between nanoparticles of the Zn metallic phase or between ZnO. Moreover, there is a clear change in the nature of conductivity at high frequencies. The photoluminescence spectra of the as-implanted Zn-SiO2-nanocomposites exhibit a blue-green band. This band is caused by the formation of oxygen vacancies in silicon dioxide. The intensity of this peak is observed to grow with the increasing annealing temperature. Besides, a strong orange-red band was revealed in the photoluminescence spectra of the annealed sample. This emission may be attributed to the presence of oxygen interstitial/antisites. The effect of thermal annealing on light-emitting properties has been discussed.