Radiation damage in ZnO ion implanted at 15K

Abstract

a b s t r a c tCommercial O-face (0 0 0 1) ZnO single crystals were implanted with 200 keV Ar ions. The ion fluences applied cover a wide range from 5 Â 10 11 to 7 Â 10 16 cm À2 . The implantation and the subsequent damage analysis by Rutherford backscattering spectrometry (RBS) in channelling geometry were performed in a special target chamber at 15 K without changing the target temperature of the sample. To analyse the measured channelling spectra the computer code DICADA was used to calculate the relative concentration of displaced lattice atoms.Four stages of the damage evolution can be identified. At low ion fluences up to about 2 Â 10 13 cm À2 the defect concentration increases nearly linearly with rising fluence (stage I). There are strong indications that only point defects are produced, the absolute concentration of which is reasonably given by SRIM calculations using displacement energies of E d (Zn) = 65 eV and E d (O) = 50 eV. In a second stage the defect concentration remains almost constant at a value of about 0.02, which can be interpreted by a balance between production and recombination of point defects. For ion fluences around 5 Â 10 15 cm À2 a second significant increase of the defect concentration is observed (stage III). Within stage IV at fluences above 10 16 cm À2 the defect concentration tends again to saturate at a level of about 0.5 which is well below amorphisation. Within stages III and IV the damage formation is strongly governed by the implanted ions and it is appropriate to conclude that the damage consists of a mixture of point defects and dislocation loops.

Doping of Ga2O3bulk crystals and NWs by ion implantation

“…High direct backscattering yields are usually ascribed to point defects, point defect clusters or amorphous zones with randomly displaced atoms. Extended defects, such as stacking faults or dislocation loops, on the other hand, lead to high dechanneling yields and low direct backscattering rates 22 . Therefore the high dechanneling yield observed for implanted Ga 2 O 3 points to the formation of extended defects in the implanted zone.…”

Interplay of defects in 1.2 MeV Ar irradiated ZnO

“…If the size of the defect clusters (isolated) is not very large but they are closely spaced then both FWHM as well as peak intensity may reduce 38 as is seen in this study. In case of such defect clusters placed in a relatively higher distance, peak FWHM may decrease with increase of coherent scattering leading to higher peak intensity 43 24 . We have also plotted the ratio (R) of peak intensities of (002) and (101) peak ( Fig.…”

Implantation Damage Formation in GaN and ZnO

“…It was shown previously that point defects and amorphous zones preferentially lead to direct backscattering at displaced atoms while stacking faults and dislocation loops rather contribute to the increasing minimum yield by dechannelling of the analyzing beam (see e.g. Feldmann, 1982;Wendler et al, 2009). Therefore, both the high dechannelling rates (Fig.…”

“…The RBS/C analysis was performed with 1. Figure 3 shows RBS/C spectra for Ar implanted ZnO (Wendler et al, 2009). The aligned spectrum of the as-grown sample is also plotted for comparison.…”

“…The occurrence of extended defects becomes especially obvious when analyzing the RBS/C spectra in more detail, which is done for Ar implanted ZnO (Wendler et al, 2009). Figure 6 plots the relative concentration of randomly displaced lattice atoms n da versus the depth z (referred to as defect profiles in the following text).…”