Firsty, surface science plays a major role and makes major contributions to various areas of energy development and technology. Surface science related problems are listed in such fields or fossil, nuclear, fusion, and solar energy technologies Sècondly, the use of thermionic energy conversion (TEC) as a topping cycle for central station powerplants is a viable option for achieving greater efficiency and, therefore, substantial fuel savings. Higher efficiency can be achieved by lower collector work functions. Oxygen at a pressure of the order of 10-6 Torr in the interelectrode space lowers the work function of the collector, improving the effidiency.
Surface science and surface technologies are reviewed from the view point that the traditional technologies for mining energy resources are “one-dimensional.”on the cther hand, the technologies applicable to “cultivate” recycle-energy are regarded as “two-dimensional”, that is surface technology. Nuclear fusion energy is essentially “three dimensional.” Typical examples of surface technology are: the selective coatings for solar heat collection, photoelectrochemical water-decomposition methods, the new power system composed of the electrolysis of HBr by solar cells, and the electric generation by the H2-Br2 fuel cell. The water-decomposition catalytic chemical cycles, such as EURATOM mark 13 and YOKOHAMA mark VII are introduced emphasizing the materials aspects. Most of the above are the current topics of innovative technology for new energy development.
During the last four years the tandem accelerator at the University of Rochester has been used as an ultrasensitive mass spectrometer in a “TIR” collaboration by the University of Toronto, General Ionex, and the University of Rochester. This extremely powerful new technique is briefly introduced. The TIR system has the advantage of extending the technique to the field of secondary ion mass spectrometry (SIMS) by incorporating a rather low voltage (2 MeV) tandem accelerator. The molecular ions whose interferences are difficult to eliminate with conventional ion microprobe mass analyzers can be fragmented and analyzed separately in surface and bulk solids. Sensitivity of TIR-mass spectrometry has been increased to detect parts per quadrillion (1015) in a sample; for the two isotopes 14C and 36Cl sensitivities are better than 1 ppq. The stable isotopes of platinum and iridium, which can already be detected to ppb (10-9) in terrestrial samples, are also being studied (Litherland and Rucklidge, 1980). An improved apparatus, called the “Tandetron”, is being built for the University of Toronto exclusively for ultrasensitive mass spectrometric studies in the whole field of scientific research.
Alloy surfaces of Cu-Au (001) and (110) are prepared by a vaporization and heating method, and are investigated by LEED. Surface structures of the hexagonal and c(2×2) typcs on the (001) surface, and (1×2), (∼4×∼1), c(3×∼1) and (2×2) on the (110) surface, are obtained by changing the mean surface composition, orresponding tructurdl models are given. In-depth distribution of atomic concentration at the Cu-Au alloy surface, after depositing gold onto the surface to the thickness of 3.3 nm with subsequent heat treatments, is presented on the basis of Fick's second law, using diffusion coefficients given by kubashewski. Theoretical treetmcnt of the surface composition change caused by annealing is compared with experiment with AES on surfaces of Cu-Au alloys over a wide composition vangc of the Cu-rich side. Surface composition given by the thoretical in-depth profiles is in agreement with that obained by experiment.
Solid phase epitaxial grouth (SPE) of vacuum-deposited amorphous silicon (a-Si) has been examined using transmission electron microscopy (TEM) and electron spin resonance (ESR). We have demonstrated that the surface cleanliness of the crystalline silicon (c-Si) substrate and impurities introduced during deposition have a great influence on the SPE process of a-Si. For a-Si deposited on a c-Si surface cleaned by iterative sputtering and annealing in ultra high vacuum, we have obtained good epitaxiai grcth layers comparable to bulk c-Si. Behavior of the EPR signal dvring annealing can be well explained on the basis of the TEM observation that there are void networks in an a-Si film deposited on c-Si having the native oxide No such structure exists in an a-Si film on c-Si with a clean surface. the structure of a-Si, where SPE occurs at a high rate, is compared with that of ion bombarded a-Si. We have discussed a mechanism of SPE on the basis of an a-Si/(100) c-Si interface model not having any dangling bonds.
An application of model catalysts has been presented as one of the methods for investigating the catalytic properties of supported metal catalysts. The model catalysts can be prepared in situ by vacuum evaporation onto an amorphous substrate (film of SiO2, Al2O3, or carbon) and studied by such techniques as photoelectron and Auger electron spectroscopy; industrial supported metal catalysts are unsuitable for such techniques using UHV systems. Ensembles prepared in this way offer the possibility of investigating not only the physical properties of particles but also their surface reactivity with simple gases. Apart from the interest in model catalysts, the small metal particles themselves deserve attention; the electronic properties of metal aggregates in size ranges where discrete valence band levels are expected have scarcely been examined. The advantages and application methods of the model catalysts are introduced as well as recent literature on the electronic properties of small metal particles and other approaches for this field.
Diffraction X-ray photoelectron spectroscopy has been introduced as a promissing technique for the analysis of surface structure. Special emphasis is placed on the applicability of the kinematical calculation to the interpretation of photoelectron diffraction from LaB6 (001) and TiC (001) surfaces. The determination of chemisorption geometry of oxygen atoms on Cu (001) surfaces is also reviewed in order to illustrate the characteristics of the diffraction X-ray photoelectron spectroscopy.
The preparation and properties are reviewed of an amorphous silicon film deposited by a glow discharge in SiH4. The amorphous silicon film prepared by this glow discharge has some properties superior to single crystal silicon. For example, it possesses a higher optical absorption, a higher dark resistivity, and a higher photoconductivity. It offers great promise for use in several semiconductor devices, especially lowcost solar cells. The photovoltaic performance of amorphous silicon solar cells is described. Today's cell conversion eflidiency of 7% is a substantial improvement over the efficiency of about 2% reported at the time of initial development in 1975. These amorphous silicon solar cells are now marketed in consumer products such as calculators. This paper also describes the application of amorphous silicon to a thin-film insulated-gate fieldeffect transistor, a visicon target, and a photo-receptor for electrophotography.