Technology Overview |
Overview: The Game Is Changing ... Natcore was formed to utilize technology, licensed from Rice University, that enables the controlled deposition of silicon dioxide and mixed silicon oxides from an aqueous solution at ambient temperatures and pressures. That’s quite a mouthful. So let’s look at it in layman’s terms... Silicon dioxide, or silica, is a fundamental building block in semiconductors, fiber optics and, of course, solar cells. It is an absolutely essential element in all these applications, and it is currently deposited onto silicon through a process called “Thermal Oxide Growth.” Simply put, this process uses complicated, multi-million-dollar furnaces, operating in a vacuum and at temperatures of up to 1,000º Celsius (1,800º Fahrenheit), to grow the necessary thin films of silicon dioxide. In contrast, Natcore’s “Liquid Phase Deposition” (LPD) process simply grows these thin films of silicon dioxide in mild chemical baths using standard, low-cost equipment. Because Natcore’s process is so relatively mild, it allows for much thinner silicon wafers, as well as the development of advanced materials and devices that would be destroyed during the standard Thermal Oxide Growth process. Natcore’s "Liquid Phase Deposition" (LPD) process was discovered at Rice University and has been independently tested and validated in an industrial laboratory setting at one of America’s most respected laboratories. In short, the technology is now ready to be tailored to specific applications. The films and processes Natcore plans to move into commercial production promise to have significant impacts on solar cells, semiconductor devices, optical and optoelectronic components, prescriptive and protective eyewear, and energy-saving architectural coatings, among many other uses. The first products are planned for the rapidly growing silicon solar cell manufacturing industry.
Making Solar Energy Economically Viable While Natcore’s "Liquid Phase Deposition" (LPD) process has many exciting potential applications, the company has decided to focus on the area where it appears to have the greatest impact: solar energy. There are two initial applications in photovoltaics where the Company’s technology could yield very significant improvements in costs and efficiencies. Photovoltaics is the technology of converting solar energy, both sunlight and ultra violet radiation, directly into electricity. First, the Company’s liquid phase deposition technology promises to allow the solar cell industry to reduce silicon wafer thicknesses by up to two-thirds — an advancement that will dramatically improve throughput and profit margins.
The key advantage that Natcore’s "Liquid Phase Deposition" (LPD) process brings is its ability to grow the crucial anti-reflective (AR) layer of a solar cell in a mild chemical bath. Current Thermal Oxide technology requires relatively thick silicon wafers because of the high heat involved. Thinner wafers often warp in this harsh environment. In contrast, Natcore’s mild process will allow wafers of only about one-third the thickness currently being used — which will translate to as much as two-thirds less silicon and significantly lower costs in materials and processing. Because the AR coating is the final step in solar cell manufacturing, and because the LPD process will utilize simple, low-cost tubs and a proprietary cartridge system, it is expected that Natcore’s process will fold easily into virtually any silicon cell production plant. The Company plans to sell materials, deposition systems and licenses based on its technology to manufacturers of silicon solar cells. Second, and perhaps much more importantly, a highly compelling application of Natcore’s technology recently emerged: The Company’s scientists have discovered that its "Liquid Phase Deposition" (LPD) process could allow, for the first time, mass manufacturing of super-efficient (30%+) tandem solar cells. For comparison purposes, these cells could achieve twice the power output of today’s most efficient solar cells. Until now, these tandem cells have been producible only under lab conditions, and at very high costs. Natcore’s process has the potential to allow their mass production at a lower cost/watt than anything available today. For reference, review the accompanying schematic of a third-generation, silicon-quantum dot tandem solar cell. Natcore envisions its LPD process allowing the manufacture of a tandem cell consisting of up to three cells arranged one on top the other, starting with an ordinary silicon solar cell on the bottom. Something called a cell interconnect comes next, then a second cell made of silicon quantum dots. This solar cell is tuned to absorb light in the middle of the spectrum, represented in the picture by the green color. A second cell interconnect follows and a third cell, another silicon quantum dot device, sits on top. This uppermost cell is tuned to absorb the blue end of the spectrum. The combination of all three operating in tandem would produce well over 30% efficiency — or about double the output of current technology.
Natcore’s edge in this process is the ability to embed the two types of silicon quantum dots in the two cells within a layer of silicon dioxide using our liquid-phase film growth process. All current and recent attempts to create viable tandem cells have used vacuum deposition techniques that are expensive and do not allow independent control over the formation of the quantum dots and the way they are arranged. That is a major disadvantage. In fact, Natcore’s "Liquid Phase Deposition" (LPD) process is what makes it possible to even consider producing a tandem cell on a commercial scale, let alone in the lab. Not only that, the full device can also utilize the Company’s proprietary AR coating deposition process, thereby realizing additional production cost savings. Through the combination of these two applications, Natcore hopes to bridge the economic gap between solar power and conventional energy production — an achievement that represents the “Holy Grail” of the alternative energy industry.
Additional Applications Present Exciting Potential The fundamental nature of the Company’s technology is enabling for a wide range of commercial applications. Essentially, any product or process that utilizes thin films of silicon dioxide or mixed silicon oxides will benefit from Natcore’s technology — and that list includes applications in semiconductors; MEMs (micro electromechanical systems); passive optical components for the all-optical internet (including fiber-to-the home telecommunications systems); architectural applications focusing on energy conservation through the controlled emissivity of architectural surfaces; all-optical interconnects for high-speed computer/server backplanes; ophthalmic lens coatings; and corrosion protection, among many others. The Company expects that the potential applications for its revolutionary "Liquid Phase Deposition" (LPD) technology will continue to branch out as a result of further research and development. Intellectual property and licensing revenues will form a foundation of its business plan. Natcore’s product development focus after silicon solar cell coatings and devices will be on products utilizing silicon substrates in one form or another. At this time, the primary potential opportunities are envisioned in the following areas: Silicon Dioxide on Silicon: SOI (Silicon-On-Insulator) Wafers A wafer technology known as silicon-on-insulator, or SOI, represents the future of microprocessor design. In SOI-based chip design, a transistor's silicon junction area is placed on top of an electrical insulator, typically silicon oxide. By thus eliminating the junction capacitance between the transistor and the silicon substrate itself, the transistor is able to operate much more quickly. Moreover, it can operate with as little as one-third the power requirements of a typical transistor on a standard silicon wafer. SOI chip production is the fastest-growing area of silicon wafer manufacturing, because faster, lower-power transistors are essential to the multitude of handheld and/or wireless devices that are already becoming pervasive consumer products. In short, the next wave of the digital revolution will be built on the back of the SOI chip, and Natcore’s technology promises to help make SOI chips more affordable. The following illustration shows a schematic cross section of a typical SOI wafer. There are a variety of ways to produce the top, or device, layer, but all processes require a pre-oxidized layer ranging in thickness from a few tenths of a micron to a few microns. (1.0 micron = 1,000 nanometers.) The substrate is a standard silicon wafer several hundred times the thickness of the buried oxide layer. The finished SOI wafer can be processed using standard wafer-fab equipment. Production of the crucial oxide layer can be accomplished using Natcore’s proprietary film-growth technology, with substantial capital and operating cost savings. Potential customers for Natcore’s technology will come from two sources: 1) existing SOI wafer suppliers, all of whom have existing manufacturing facilities producing their current product, and 2) potential new SOI wafer suppliers who will enter as the market grows. Although the present volume of the SOI wafer market does not represent an important source of revenues for Natcore, the application is straightforward, and worth the effort to position the Company to enter it as soon as practicable. Semiconductor device market analysis firms unanimously predict that SOI wafers will eventually supplant ordinary silicon wafers in the long term. Were that to occur, SOI wafers would eventually represent a potential hundred-million-dollar-per-year market for the Company. Optical Components Businesses and individuals worldwide are demanding higher-speed communications and data-handling capability. The widely accepted solution for meeting such demand is the use of dense wave division multiplexing (DWDM) in an all-optical Internet. The all-optical Internet infrastructure has three main segments: long-haul, fiber-optic trunk lines; citywide and local-area fiber-optic rings; and the well-known “last-mile” fiber-optic branches that connect to the users. While installations of the long-haul and citywide segments are underway in the U.S., Japan and Europe, the last-mile segment has not yet been adequately addressed. A broad range of both active and passive DWDM optical components is needed to complete this segment of the infrastructure, and represents by far the largest market for such devices. (All three segments require the devices.) Products are already under development by many companies to meet the ever-growing demand. But the key element does not yet exist: a high-volume manufacturing technology that can create components at low-enough cost to entice end-users to upgrade from the electronic Internet connections they now have. The Company believes it has precisely that technology. The highest-performing optical components are made from high-purity silicon dioxide, with controlled amounts of additives used to create the desired functionality in any particular class of device. An arrayed waveguide is an excellent example: The usual process for making the device is deposition of a multi-layer, SiO2 structure on a silicon wafer. The transmission, or core, layer is thicker and has a higher index of refraction compared to the thinner buffer layer between it and the silicon wafer substrate. The core layer is coated with a cladding layer identical to the buffer layer. The illustration below depicts a cross section of a typical waveguide structure. Currently, deposition of the core and cladding layers is accomplished by flame hydrolysis of silicon tetrachloride (with or without additives, depending on the value of refractive index needed for the layer) into silicon dioxide. The deposition process itself takes high temperatures (>900 °C), after which the deposited film must be densified at elevated temperatures for an extended period of time. Deposition uniformity requirements limit process chamber sizes, so only a limited number of wafers (typically six or less) can be handled at one time. Increased production volume is achieved by operating multiple chambers simultaneously, providing little or no economy of scale. In contrast, Natcore’s film growth technology enables optical-quality silicon dioxide films to be grown over large areas and on large numbers of wafers simultaneously, providing huge economies of scale and a concurrent reduction in costs. Furthermore, because the growth proceeds at ambient temperature, several patterning and processing steps can be combined to further reduce costs. The result promises to be lower manufacturing costs for high-performance, silicon dioxide-based optical devices by a very significant margin compared to current production techniques. The Company has several options to generate revenue in this rapidly growing market. The fastest and least capital-intensive path to market is through licensing Natcore’s growth technology to original equipment manufacturers. The array of planar components to which the technology applies is extensive: modulators, attenuators, couplers, splitters, arrayed waveguides, tunable lasers, erbium-doped fiber amplifiers, add/drop optical mux, variable optical attenuators, etc. Even though margins are all-important in the current market environment, optical equipment remains costly. According to several market analysis firms, the reason is straightforward: Manufacturability of components still has a long way to go. To address this situation, two things must happen: 1) technology must be developed to enable discrete devices to be integrated into planar lightwave circuits, or PLCs; and 2) a low-cost manufacturing process for optical components must be developed. Securing these advances will offer tremendous opportunities for component vendors to capture significant market share for their products.
Use of Natcore’s technology represents a potential breakthrough in cost that could spawn dramatic growth in this market. The Company’s film growth technology requires no vacuum or high-temperature processing, making it an enabling technology for low-cost production of PLCs. Such a situation works in Natcore’s favor for securing favorable license terms.
Other High-Priority Applications The report prepared by one of the world’s most respected science and technology laboratories following their independent testing and verification of Natcore’s "Liquid Phase Deposition" (LPD) technology included suggestions for potential commercial applications and products. As you can see from the following list, these suggestions included some of the applications currently being considered as high priorities by Natcore, as well as a number of additional applications with exceptional long-term potential: Waveguides, including waveguide cladding, and other passive optical components for the all-optical Internet. Specialized coatings for solid state lasers and other non-silicon semiconductor devices. (There is a need for coatings that will extend the useful lifetime of such devices.) Internal oxide layers for silicon semiconductor devices (i.e., computer chips) Liquid phase deposition oxides for microelectromechanical (MEMs) device fabrication. (There is a need for low-temperature oxide deposition.) Protective coatings for plastic lenses of all sorts, from prescription eyeglasses to over-the-counter sunglasses and reading glasses. Cladding for both large- and small-scale metallic surfaces. Large-scale surfaces include metal liners for hot water heaters, and small-scale surfaces include copper traces on circuit boards to turn them into easily patterned optical waveguides. Protective coatings for light emitting diodes (LEDs) that emit red, yellow and especially white light. (These devices will eventually replace the incandescent light bulb in automobiles and homes and represent a huge consumer market.) Antireflecting coatings for silicon solar cells. Films to control the emissivity of windows and architectural glass surfaces. (Emissivity control affects the amount of light and heat that can move through a sheet of glass.)
Natcore FAQs The following are a series of frequently asked questions about the Natcore liquid phase deposition process. We’ve found that the answers to these questions help to explain what the Natcore process is, and what it is not. Q. Is this a sol-gel process? A. No, this is not a sol-gel process. Natcore’s process is a development of a process called liquid phase deposition (LPD).
Q. How does Natcore’s process differ from a sol-gel process? A. The sol-gel process requires the reaction of an organic-containing precursor that results in the incorporation of impurities into the sol-gel formed material. These impurities must be removed by pyrolysis. In contrast, Natcore’s process uses no organic compounds and, therefore, the associated impurities cannot be incorporated.
Q. Has LPD been used before? A. Yes, successfully by a number of research groups. However, unlike prior research in this area, Natcore’s patent-applied for and proprietary technology allows for faster growth rates to be maintained over a long reaction time.
Q. Is purity of the film the only difference between sol-gel and Natcore’s process? A. No, the sol-gel process results in homogeneous nucleation, causing solids to form within the solution instead of on the desired surface. These particles formed in solution then drop onto the surface being coated, causing defects. In contrast, Natcore’s process is shown to react by heterogeneous nucleation at the interface between the growth surface and the reagent solution. Therefore, Natcore’s process grows a film at the surface, where the film is required.
Q. Is this is a slow process? A. Traditional liquid methods give fast film growth initially, but the rate of growth then slows. In contrast, Natcore’s technology allow for faster growth rates to be maintained over a long reaction time. Q. What are your competitive advantages over other processes?
Q. What are your competitive advantages over other processes? A. The technical advantages of Natcore’s process in comparison with other solution methods (such as sol-gel) are higher purity, greater film uniformity and deposition rate. The advantages of Natcore’s process in comparison with vapor methods (such as high temperature oxidation) include the use of a lower-energy process, the use of well established methods, and the use of low-cost equipment that is typical of a semiconductor device FAB facility.
Q. Does that relate to a commercial advantage? A. Yes, Natcore believes that our initial competitive advantage will be sharply reduced costs and dramatically increased throughput for oxide film growth.
Q. Will this need a large financial commitment for implementation? A. No, the chemicals used in Natcore’s process are all typically found in a FAB facility and are readily purchased in high purity. The equipment that will be used for Natcore’s process is the same as that used in all FAB facilities in the world for cleaning and etching silicon wafers.
Q. Isn’t the silicon-on-insulator (SOI) process a multi-step and very complex technology? Does any one step really make an impact? A. Yes, there are many steps. However, the SOI wafer producers are searching for any and all cost-reduction techniques and technologies since their competition is so great.
Q. Is Natcore’s process limited to coating silicon wafers? A. No, part of Natcore’s process is the ability to deposit a coating on a range of metal substrates. Among potential applications, this enables is the formation of circuits of optical interconnects on computer circuit boards using their present metal interconnects as guides.
Q. Is the technology protected by patents? A. Yes, Natcore has an exclusive license from Rice University for the technology.
Q. What degree of coverage does the Patent have? A. The patent has been granted in Russia and is pending in the U.S., Europe and other countries. Natcore has performed extensive patent and literature searches and believes that our patents will be issued.
Q. Are there any applications not covered by our agreement with Rice? A. Natcore has certain proprietary technology that it intends to file in the U.S., Europe and other countries. At present this proprietary technology has either been filed as provisional patent applications or is being kept as trade secrets. The rights to this additional technology are exclusively owned by Natcore.
Q. Everything in the current state of the art argues against your claims. Experience shows that greater heat and more extreme pressure differentials yield progressively better oxide films. How can you make such a claim that flies in the face of all previous experience? A. Yes, this process is opposed to current high-energy consumption methods. And that’s precisely why it is such a compelling technology, and has such important implications going forward. Natcore has taken an approach similar to nature. Man-made materials (oxide formed by high temperature oxidation) are formed under extreme conditions. In contrast, nature uses low-energy-designed pathways to make materials with high purity.
Q. So it’s a new approach, but isn’t it just a curiosity from a professor’s laboratory? A. While Natcore’s process was originally developed in Professor Barron’s laboratory within the Center for Nanoscale Science and Technology at Rice University, Natcore has put the process through rigorous, independent testing by a globally respected laboratory.
Q. What are the results of these independent tests? A. The independent laboratory, Battelle Memorial Institute, was able to scale up the process as developed by Professor Barron and uniformly coat multiple wafers in a single reaction bath. They were able to quickly replicate Professor Barron’s results and improve the scale and film purity. The films have passed all tests with flying colors, including analyses of uniformity, growth rates, conductivity, reproducibility and early-stage testing for purity.
Q. Have additional tests been performed? A. Yes, two additional independent labs have been used for confirmation of the film purity. |