Ne–He bubble formation in co-implanted Si(111) substrates

• We investigated Si(111) narrowly implanted (150 nm) with Ne, He and mixture of both.
• Only (1 × 1015 cm− 2 Ne & 1 × 1016 cm− 2 He) set showed some He like thermal behavior.
• Hybrid bubble morphology is very alike to Ne bubbles even for ratio 1Ne:10He.
• Hybrid bubble morphology does not recall any similarity to the He system.
• Residual implantation damage makes role on the hybrid system.

We have studied Si(111) substrates co-implanted with Ne and He, and also separately implanted with these ions, as a function of the annealing temperature. Ne implantations were performed up to fluences of 1 × 1015 and 5 × 1015 cm− 2 while keeping the substrate at 350 °C temperature. He implantations were performed at room temperature up to fluences of 5 × 1015 and 1 × 1016 cm− 2. The co-implanted samples were first implanted by Ne and then by He ions. These samples were submitted to rapid thermal annealing with temperatures ranging from 350 to 1000 °C. Rutherford backscattering spectrometry/channeling measurements have demonstrated temperature dependent beam dechanneling starting at the implanted ion region. The co-implanted system with 1 × 1015 Ne/cm2 and 1 × 1016 He/cm2 shows an improved dechanneling stability in the range of 400–800 °C. Transmission electron microscopy has demonstrated a bubble morphology of Ne–He similar to the sample implanted only with Ne, even for a Ne:He co-implantation ratio of 1:10. We have concluded that the observed dechanneling is mainly due to Ne residual implantation damage and that the annealing behavior of such systems is very different from the He implanted samples.