Nanocrystalline SiC formed by annealing of a-SiC:H on Si substrates: A study of dopant interdiffusion
Nanocrystalline silicon carbide (nc-SiC) is an interesting material for electronics applications, both in its own right and as a host matrix for silicon quantum dots. When synthesized by annealing of a-SiC:H on Si substrates, interdiffusion of dopants occurs if either the a-SiC:H or the Si substrate...
| Κύριοι συγγραφείς: | , , , , , , |
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| Μορφή: | Journal article |
| Γλώσσα: | English |
| Έκδοση: |
American Institute of Physics Inc.
2014
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| Περίληψη: | Nanocrystalline silicon carbide (nc-SiC) is an interesting material for electronics applications, both in its own right and as a host matrix for silicon quantum dots. When synthesized by annealing of a-SiC:H on Si substrates, interdiffusion of dopants occurs if either the a-SiC:H or the Si substrate is doped. Annealing a-SiC:H on highly boron-doped substrates at 1100°C leads to a fairly homogeneous doping level of ≥ 4×10 19cm-3 throughout the nc-SiC film. An unexpected anomaly in secondary ion mass spectroscopy quantification is observed and a method to circumvent it is shown. The nanostructure of the nc-SiC is only weakly affected as most of the diffusion occurs after the onset of crystallization. Annealing of doped a-SiC:H on Si substrates at 1100°C leads to strong free carrier absorption at infrared wavelengths. This is demonstrated to originate from dopants that have diffused from the a-SiC:H to the Si substrate, and a method is developed to extract from it the doping profile in the Si substrate. The detection limit of this method is estimated to be ≤6×10 13cm-2. Doping levels of (0.5-3.5)×10 19cm-3 are induced at the Si substrate surface by both boron and phosphorus-doped a-SiC:H. When the Si substrate is doped opposite to the a-SiC:H p-n junctions are induced at a depth of 0.9-1.4μm within the Si substrate for substrate resistivities of 1-10 Ω cm. Implications for different solar cell architectures are discussed. Dopant diffusion can be strongly reduced by lowering the annealing temperature to 1000°C, albeit at the expense of reduced crystallinity. © 2014 AIP Publishing LLC. |
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