PDF Publication Title:
Text from PDF Page: 013
The chemical, structural, and electrical properties of the c-Si/a-Si interface in Si HIT cells: In collaboration with NREL’s Si Group, the microstructure and interface properties of Si heterojunction (SHJ) cells were investigated. Such cells have recently demonstrated world- record efficiency on single-side, untextured Si HIT structures. The atomic structure and electronic properties of the crystalline silicon/hydrogenated amorphous silicon (c-Si/a-Si:H) interface were examined by high-resolution transmission electron microscopy (HRTEM), atomic-resolution Z- contrast imaging, and electron energy loss spectroscopy. We found that all high-performance SHJ solar cells exhibit atomically abrupt and flat c- Si/a-Si:H interfaces and high disorder of the a-Si:H layers. These atomically abrupt and flat c-Si/a-Si:H interfaces can be realized by direct deposition of a-Si:H on c-Si substrates at a substrate temperature below 150°C by hot-wire chemical vapor deposition from pure silane. Figure 2(a) shows a Z-contrast image of the front (100) c-Si/a-Si:H interface in a double- heterojunction SHJ solar cell with a high Voc of 680 mV. The intrinsic and doped a-Si layers are not distinguishable in the images. On the c-Si side, the elongated bright spots directly represent the two closely spaced (110) silicon columns, or silicon “dumbbells.” The amorphous feature is shown as continuous background in the Z-contrast image. Combining this Z-contrast image with other HRTEM images, we conclude that the interface is atomically abrupt and flat. To understand the electronic structure change across the interface, EELS spectra were taken at different points around the interface. Figure 2(b) shows the Si-L edges spectra taken from three points indicated as p1, p2, and p3 in Fig. 2(a). Point 1 is inside the a-Si:H layer, point 2 is at the interface, and point 3 is inside the c-Si. It is seen that the intensity of the first peak (as indicated by black arrows) is reduced as the electron beam is moved from the c-Si region to the interface. It is further reduced when the electron beam is moved into the a-Si:H layer. The Si-L edges spectra represent the transition from the silicon 2p band to the conduction band. The intensity reduction of the first peak indicates that the density of states is reduced around the minimum of the conduction band. The reduction at the interface and in the a-Si is likely caused by the disorder. Thus, the intensity of this peak tells us the quality of the a-Si:H layer, i.e., the lower the intensity, the more disorder, i.e., better a-Si. The 7 EELS spectra in Fig. 2(b) indicate a high-quality a- Si:H layer is achieved. a-Si c-Si (a) (b)100 Fig. 2. (a) Z-contrast image of the front c-Si/a-Si:H interface in a double-heterojunction SHJ solar cell, and (b) Si-L edges spectra taken from different points around the c-Si/a-Si:H interface. 3.2 Cell and Module Performance Task ISO 17025 Accreditation for secondary cell calibrations (MYTP M-4, T-1): The Cell and Module Performance Group achieved a very significant priority 3 milestone by expanding ISO 17025 accreditation to include primary reference cell and secondary module calibration under ASTM and IEC standards. The American Association for Laboratory Accreditation (A2LA) awarded the accreditation to NREL on September 12, 2005. Quality calibration plays a critical role in the product-manufacturing process. ISO accreditation provides our customers with confidence that the performance reported for these products is verifiable and internationally accepted. Many of our PV industry partners currently have ISO 9001 quality programs in place. These companies rely on NREL for calibrations of reference cells and modules they use to measure their products. Certified module qualification facilities such as Photovoltaic R&D Fundamental Research p1 p2 p3 1 nm 150 200 Energy (eV) p1 p2 p3 Counts (ab)PDF Image | DOE Solar Energy Technologies Program
PDF Search Title:
DOE Solar Energy Technologies ProgramOriginal File Name Searched:
38743.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)