An optical study of the D—D neutron irradiation-induced defects in Co- and Cu-doped ZnO wafers

Abstract

Room-temperature photoluminescence and optical transmittance spectroscopy of Co-doped (1 × 10 14 , 5 × 10 16 , and 1 × 10 17 cm −2 ) and Cu-doped (5 × 10 16 cm −2 ) ZnO wafers irradiated by D-D neutrons (fluence of 2.9 × 10 10 cm −2 ) have been investigated. After irradiation, the Co or Cu metal and oxide clusters in doped ZnO wafers are dissolved, and the würtzite structure of ZnO substrate for each sample remains unchanged and keeps in high c-axis preferential orientation. The degree of irradiation-induced crystal disorder reflected from the absorption band tail parameter (E 0 ) is far greater for doped ZnO than the undoped one. Under the same doping concentration, the Cu-doped ZnO wafer has much higher irradiation-induced disorder than the Co-doped one. Photoluminescence measurements indicate that the introduction rate of both the zinc vacancy and the zinc interstitial is much higher for the doped ZnO wafer with a high doping level than the undoped one. In addition, both crystal lattice distortion and defect complexes are suggested to be formed in doped ZnO wafers. Consequently, the Co-or Cu-doped ZnO wafer (especially with a high doping level) exhibits very low radiation hardness compared with the undoped one, and the Cu-doped ZnO wafer is much less radiation-hard than the Co-doped one.

Dielectric spectroscopy studies of ZnO single crystal

“…[1] The existence of vacancy oxygen has been revealed by photoluminescence (PL) spectroscopy and other experiments. [1,[4][5][6][7][8][9] Since the trap energy level E T in the forbidden band is almost fixed for a certain material, the activation energy (E C -E T ) for trapped electron relaxation is almost invariant. [1,10] Therefore, it can be deduced reasonably that the loss peak in ZnO single crystal originates from oxygen vacancies.…”

Enhanced ultraviolet photoresponse based on ZnO nanocrystals/Pt bilayer nanostructure

“…[21][22][23] As is well known, chemiabsorption sites and oxygen vacancies are the main factors regulating the photosensitivity of the ZnO film. [24][25][26][27][28] The influences of microstructure and crystallographic orientation on the chemiabsorption sites and oxygen vacancies have been investigated in Refs. [29] and [30].…”

Oxygen vacancy-induced room-temperature ferromagnetism in D—D neutron irradiated single-crystal TiO 2 (001) rutile

“…[19,20] Recently, we have reported optical properties of D-D neutron (2.5 MeV) irradiation effects on Co-doped ZnO wafers. [21] The Co metal and oxide clusters were dissolved with a great number of induced defects coherently throughout the wafers after the irradiation. In addition, no other effects, neutroninduced nuclear reaction for example, were detected.…”

“…D-D neutrons can easily pass through SCR leaving defects distributed homogeneously. And what is more, it was proved to be a much cleaner way of creating defects [21] than other ions [22] (e.g., N-, Ar-), because neutron activation cross sections at 2.5 MeV in SCR are very low and can be neglected (data from National Nuclear Date Center). Our results strongly suggest that V O should be related to RTFM in SCR, for the samples are pure enough after D-D neutron irradiation.…”