C⁺-damaged diamond: electrical measurements after rapid thermal annealing to 500°C

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• 作者：Prins ; Johan F.
• 关键词：Diamond ; Ion-implantation ; Radiation damage ; Graphitisation
• 刊名：Diamond and Related Materials
• 出版年：2001
• 出版时间：March - July, 2001
• 年：2001
• 卷：10
• 期：3-7
• 页码：463-468
• 全文大小：133 K

文摘

C⁺-damaged diamond layers were generated in natural type IIa diamonds by means of ion-implantation at liquid nitrogen temperature followed by rapid thermal annealing to 500°C. The resistance behaviour of these layers was then studied as a function of C⁺-ion dose. It was found that the postulated graphitisation threshold of 10²² cm⁻³, as simulated by the TRIM computer program, could be exceeded by a large margin before such a layer became graphite when annealed at temperatures higher than 500°C. Variable range hopping conduction, ascribable to intrinsic defects, could be measured below the graphitisation threshold. The results indicate that at low doses the density of these hopping centres N(E_F) relates to the wave functions (with radial extent α) of individual vacancies. At higher doses α³N(E_F) started to decrease. This may be attributed to the formation of extended, vacancy-rich regions that act as single hopping centres. In one of the diamonds implanted, the latter process seems to have dominated up to the highest C⁺-CIRA ion dose of 1×10¹⁶ cm⁻² used in this study. Only at this dose did the layer become graphitic during subsequent higher temperature anneals. In the latter case, the equivalent vacancy density corresponded to 7×10²² cm⁻³.