Emerging Markets for Silicon Nanomaterials and Nanostructures
By Lawrence D. Gasman, principal analyst, NanoMarkets LC
Many nanomaterials are currently prescribed to solve problems or create new markets in the semiconductor industry. We believe that nanocrystalline silicon (aka nanosilicon) has perhaps the greatest potential returns because it is based on same material that is the foundation of the electronics industry. In a time when the investment community is extremely risk-averse and very particular about where to invest, the fact that silicon is familiar works to the advantage of nanocrystalline silicon. In some cases, NanoMarkets believes that commercialization of nanocrystalline silicon is less than one year away. Other nanomaterials suffer more from a longer time horizon for commercialization and the short-term focus of most funding sources today. This paper reviews the applications that we see as the biggest opportunities for nanosilicon.
Photovoltaics (PV) is currently the most promising opportunity for nanosilicon. PV offers high conversion efficiencies while still benefiting from silicon's relatively low cost. Tunable nanosilicon particles can also contribute to higher-efficiency tandem or multi-junction PV cells, and other morphologies— nanorods and nanowires— offer to boost efficiency even further. In addition, CIGS and organic PV have yet to reach their potential, so there is an early opportunity for nanosilicon PV to enter the fray— offering high-performance, moisture-insensitive flexible technology for building integrated PV applications. In another development, nanocrystalline/crystalline hybrid cells are being commercialized and may boost wafer-based silicon PV cells to a new, higher level of conversion efficiency. Important in the context of PV is the fact that nanocrystalline silicon PV can make a strong claim as a "green technology" in that it does not rely on scarce or toxic metals like CIGS PV and CdTe PV..
Meanwhile, the nonvolatile memory industry is anxiously seeking options to allow continued scaling of memory arrays beyond what is possible with conventional floating-gate memory technology. One answer to this problem is using silicon nanocrystals as the floating gates, making charge retention more robust and reducing the thickness of gate oxide required to prevent leakage. However, even if nanocrystalline floating gate memories make significant penetrations into the nonvolatile memory market, the nanocrystals that are used do not necessarily need to be silicon; metal nanocrystals can also function here and there is some suggestion that they could even be faster. Metal gates are becoming accepted in the logic fabs, so it is likely that this acceptance will lower the penetrations of nanocrystalline silicon into the memory market. However, the memory market is so large that, even at low levels of penetration, device-level revenues generated by nanocrystalline silicon floating gate memories are likely to be larger than those of the other categories of nanocrystalline silicon products, excluding photovoltaics.
Most of the companies developing nanocrystalline silicon— especially inks— also have some plans for the TFT market. This is understandable because the conventional silicon TFTs used in active matrix displays are rather costly to build. Some efforts have focused on using amorphous silicon instead or polycrystalline silicon, underscoring the entrenchment of silicon in this industry and the willingness to try other forms of it to pursue lowered costs. Other efforts have switched to organic TFTs, but the performance of these devices is in the best cases only equivalent to amorphous silicon. Nanocrystalline silicon offers a high likelihood of decent performance at lower cost, especially if it is printed.
While the above are the main areas in which we can expect nanocrystalline silicon to do well, there also the possibility of using this material to create some form of lighting. The problem is that nanosilicon lighting will face strong competition from light emitting diodes manufactured either with Gallium Nitride or an organic semiconductor. NanoMarkets believes, however, that if a company does eventually begin to take steps toward commercializing nanocrystalline silicon lighting, it is most likely to be a nanocrystalline silicon PV player.
It is also important to consider how nanosilicon devices will be manufactured. Printing is talked about a great deal and is primarily seen as a way to reduce costs. However, functional printing has not developed as fast as some people expected a few years back and more conventional deposition methods that do not differ tremendously from the deposition of conventional silicon in terms of the basic design of the equipment used are most likely to be deployed today. Hence, much of the same equipment that is being used for the deposition of conventional silicon films may also be suitable for nanocrystalline silicon film deposition. The opportunity that this presents is obvious: firms using conventional silicon films for devices like TFTs or PV cells may be able to begin developing nanocrystalline silicon processes with only modest— instead of huge— outlays for new equipment. This is likely to accelerate the development of commercial nanocrystalline silicon devices since the capital risks are lessened.
With the potential of providing new business revenue in the PV, memory, TFT and (perhaps) the lighting segment, nanosilicon is a material that carries within it considerable opportunities for the semiconductor industry.
For additional details about the recent NanoMarkets report, "Opportunities for Nanosilicon: 2009 to 2016," please visit www.nanomarkets.net.
January 5, 2010