Evolution of Helium Bubbles and Discs in Irradiated 6H-SiC during Post-Implantation Annealing.

Ning Li,Qijie Feng,Ruixiang Li,Wei Zhou,Qiang Shen,Guang Ran

doi:10.3390/ma10020101

Abstract

The single crystal 6H-SiC with [0001] crystal direction irradiated by 400 keV He+ ions with 1 × 1017 ions/cm2 fluence at 400 °C were annealed at 600, 900, 1200 and 1400 °C for different durations. The evolution of helium bubbles and discs was investigated by transmission electron microscopy. An irradiated layer distributed with fine helium bubbles was formed with a width of ~170 nm after helium ion irradiation. The size of gas bubbles increased with increasing annealing time and temperature and finally reached stable values at a given annealing temperature. According to the relationship between the bubble radii and annealing time, an empirical formula for calculating the bubble radii at the annealing temperature ranged from 600 to 1400 °C was given by fitting the experiment data. Planar bubble clusters (discs) were found to form on (0001) crystal plane at both sides of the bubble layer when the annealing temperature was at the range of 800–1200 °C. The mechanism of bubble growth during post-implantation annealing and the formation of bubble discs were also analyzed and discussed.

Highlights

There have been considerable efforts devoted to the development of SiC for nuclear energy applications by utilizing its unique physical and chemical properties
The lattice damages are significantly recovered while the increased size of helium bubbles is very small after annealing for 30 min at 600 ◦ C
Ions with 1 × 1017 ions/cm2 fluence at 400 ◦ C and subsequently annealed at 600, 900, 1200 and 1400 ◦ C for different durations was analyzed by transmission electron microscopy

Summary

Introduction

There have been considerable efforts devoted to the development of SiC for nuclear energy applications by utilizing its unique physical and chemical properties. Zhang et al [9] investigated the dependence of helium-defect formation with ion fluence in 4H-SiC. Materials 2017, 10, 101 mechanism of helium bubbles should be systematically investigated with different annealing temperature and time. At 1273 K annealing temperature, Li [14] observed the formation of bubble discs in the irradiated area of 6H-SiC irradiated with about 3 × 1016 He+ /cm fluence. Strain induced by helium implantation in SiC crystal affected the evolution of irradiation defects during ion implantation and subsequent annealing [15]. The detailed evolution behavior of bubble discs has not been fully investigated during post-implantation annealing. 6H-SiC irradiated with 1 × 1017 ions/cm fluence were investigated during the annealing process. The relationships between average bubble sizes and annealing parameters such as temperature and time were analyzed

Experiments

Results and Discussion

Bright

Conclusions

Methods