On the nature of ion implantation induced dislocation loops in 4H-silicon carbide

Abstract

Transmission electron microscopy was used to investigate B11, C12, N14, Al27, Si28, and Ar37 ion-implanted 4H-SiC epilayers and subsequent defect formation after high temperature annealing. During the annealing process extrinsic dislocation loops of interstitial type are formed on the SiC basal plane with a depth distribution roughly corresponding to the distribution of the implanted ions. The investigation reveals that in samples where the implanted ions are substituting for a position in the silicon sublattice, generating an excess of interstitial silicon, the dislocation loops are more readily formed than in a sample implanted with an ion substituting for carbon.

Proton irradiation study of GFR candidate ceramics

“…In the Kr ion irradiation, well defined loops are only exhibited in SiC irradiated to 70 dpa. According to Persson's work [4], these loops are most likely interstitial loops residing on (0 0 0 1) planes. Since loops only developed at very high dose in Kr irradiated SiC, the dose for proton irradiation to 0.71 dpa may be too low to see the loops.…”

“…They found loops at fluences above 2.6 Â 10 14 ions/cm 2 and these loops reside on the (0 0 0 1) basal plan with average size of approximately 50 nm. They also reported that the loops in 4H-SiC consist of C, or Si self-interstitials, or both [4].…”

A view of the implanted SiC damage by Rutherford backscattering spectroscopy, spectroscopic ellipsometry, and transmission electron microscopy

“…4͑a͔͒ is very characteristic for small dislocation loops of extrinsic type. It is already known 13 that Al is not concentrated in the loops, therefore those were formed by Si accumulation. This is attributed to activation of the Al atoms by taking substitutional sites creating Si interstitial.…”

Gas-Cooled Fast Reactor (GFR) FY05 Annual Report

“…They found loops at doses above 2.6x10 14 ions/cm -2 and the loops reside on (0001) basal plan with average size of approximately 50 nm [8]. They also reported that the loops in 4H-SiC consist of C or Si self-interstitials, or both [9].…”

“…The average loop size for SiC at 70 dpa is roughly half of the loop size in TiN at 70 dpa. According to the work by Persson [9], these loops are most likely interstitial loops residing on (0001) planes. From the picture in Figure 19, the loops appear all in the shape of circular discs.…”