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They¿ve long been a girl's best friends, but now diamonds might just win over electrical engineers, too. According to a report published in the current issue of the journal Science, researchers have succeeded in fabricating films of synthetic diamond that have properties similar to those of silicon. The results, muses Gehan A. J. Amaratunga of Cambridge University in an accompanying commentary, "could be a watershed for carbon electronics."
Diamond-based electronics would be preferable to their silicon counterparts because diamond exhibits greater heat resistance and incredible hardness. But natural diamonds have too many faults and impurities to be used as semiconductors. And although scientists have been able to manufacture synthetic diamonds since 1955, current techniques create a diamond comprised of many small crystals. The borders between these crystals interfere with electron flow and have so far hampered development of electronic devices based on carbon. In the new work, Jan Isberg of the ABB Group Services Center in Sweden and his colleagues modified an existing diamond-manufacturing technique known as microwave plasma chemical vapor deposition. They grew their thin film on top of another diamond, which aided in the alignment of the film's carbon atoms. By adding diborane gas (a mixture of hydrogen and boron) the researchers introduced "holes" into the crystal structure that allowed electrons to flow uninhibited. Indeed, the team found that their films had mobility values (which measure current flow) that were the highest yet measured for diamond. The results, the authors write, "represent a major step toward the realization of viable diamond electronic devices."
Even if the process can be successfully scaled up for industrialization, it is unlikely diamond chips will replace today's silicon ones. Instead, they will most likely be developed for specialized applications such as radar or satellites, which require high-power performance at high temperatures.
