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The cost of solar cell production can be reduced by wafer thinning. A thinner wafer provides flexibility, and crystalline silicon solar cells are promising as flexible solar cells due to their flexibility. However, as wafers become thinner, production yield decreases due to wafer breakage caused by sawing damage; thus, to further reduce wafer thickness, it is necessary to suppress sawing damage. We investigated the flexibility of wafers under various slice conditions by conducting biaxial bending tests and clarified the dominant factor causing sawing damage to further reduce the wafer thickness for crystalline silicon solar cells. The results of damage observation by scanning electron microscopy and evaluation of the crystal structure by Raman spectroscopy confirm that the damage structure changes significantly depending on wire specifications. The results from the biaxial bending tests indicate that the three-dimensional flexibility of a wafer is determined by wire specifications.

In this study, we evaluated sawing damage of thin silicon wafers. Ultra-thin silicon wafers with great advantages of bendability and lightweight are suitable for needs such as to realize PV-powered vehicles. For thin wafers, it is important to realize high precision slicing to prevent breakage. We evaluated the distribution of sawing damage and crystallinity in order to clarify the cause of wafer breakage and establish low damage slice conditions. We confirmed phase transformation of silicon and crystalline defects on wire exit side on the conventional slicing surface, while the advanced slicing surface shows almost only single-crystalline Si phase.

Komatsu NTC developed ultra-thin wafer slicing with low kerf-loss by multi diamond-wire saw. We modified slicing conditions and diamond-wire specifications to keep the straightness of wire for the fine pitch slicing and established 150 μm pitch slicing technology. The as-cut wafer thickness is 90 μm, and the kerf-loss is 60 μm. As a result, the highly flexible ultrathin wafer can be obtained with well-controlled surface crystallinity. The PERT cell fabrication trial using ultra-thin wafers showed that the relative deference of cell efficiency between 166 μm thick and 84 μm thick solar cells was just only 1.2%.

The high quality and thin Si wafer technology for the future higher conversion efficiency and lower cost crystalline silicon solar cells are realized. The high minority carrier lifetimes even after the processes are obtained by controlling the Czochralski growth condition, which prevents the interstitial oxygen segregation enhanced by the substitutional carbon. The Cz ingot is sliced by the advanced diamond multi-wire saw technology and the thin wafers with relatively thin damaged layer and 100μm kerf-loss are realized. The thin wafer with low kerf-loss decreases the wafer cost and improve the cell performance. The thin wafer solar cells are fabricated using the PERC processes, and these technologies are evaluated from the view point of photovoltaic.

The impact of Si wafer thickness on the photovoltaic performance of hydrogenated amorphous silicon/crystalline silicon (a-Si:H/c-Si) heterojunction solar cells was examined from the optical and electrical points of view. Optical characterization of c-Si wafers of various thicknesses showed that a realistic light-trapping scheme, i.e., pyramidally textured Si wafers with a dielectric antireflection coating and a back reflector, realizes an efficient quasi-Lambertian light absorption enhancement, even for very thin wafers. This indicates that high photocurrent densities are achievable by using the realistic light-trapping scheme, assuming that the parasitic absorption loss is minimized. The potentials of open-circuit voltage (V OC) and the fill factor (FF) of thin c-Si cells were investigated using thin c-Si wafers passivated with intrinsic/doped amorphous silicon film stacks. It was experimentally confirmed that the implied V OC increases steadily with decreasing wafer thickness down to 30 µm, while the implied FF weakly depends on the thickness. As a result of the trade-off between light absorption and implied V OC, a high implied efficiency is expected for a wide range of wafer thicknesses. The V OC increase by thinning the wafer was also experimentally confirmed in an a-Si:H/c-Si heterojunction cell with a thickness below 60 µm, resulting in a conversion efficiency of 21.0%.

A 54-year-old Japanese female developed granuloma annulare twice in herpes zoster scars. Soon after the second event, she developed ulcerative colitis, which was well controlled by sulfonamides and corticosteroid suppository. She had no history of diabetes mellitus. There was no recurrence of granuloma annulare by June of 1999. Granuloma annulare might have contributed to the complications of ulcerative colitis, although this had not been noticed before.

Simultaneous occurrence of bilateral axillary Paget's disease in a 61-year-old male with genital Paget's disease of 2 years' duration was presented. Invasive adenocarcimoma was found in the genital lesion. No regional lymph node metastases ware apparent. The lesions were excised in toto. There has been no recurrence 14 months later. Four previously reported cases of double or triple extramammary Paget's disease, together with two more cases were summarized. Generally, the axillary lesions were clinically insignificant, faintly erythematous patches and could hardly be identified without histological examination.

組織学的に結節性動脈周囲炎(PN)の所見を示す炎症性皮膚結節10例について皮膚, 皮膚以外の臨床像, 臨床検査成績, および臨床経過を調べた。その結果, 臨床症状には症例による差異がみられ, 軽度の腎症状, 高血圧が認められる症例やベーチェット病の疑いが持たれる症例などが認められた。初診後2ヵ月から5年6ヵ月間の観察で生命にたいする予後は良好であつたが, 皮膚症状は難治であり, 有病期間が30年を越える症例もみられた。自験例と文献的考察により皮膚型PNの独立には再考の余地があると考えられた。

A Japanese girl, 2 years, 8 months of age, with palmoplantar keratosis and dendritic corneal opacities, showed increased tyrosine levels in the plasma, urine, and cerebrospinal fluid. The mental and physical growth was riot retarded. The hepatorenal functions were within normal limits. Electron microscopically, the epidermal keratinocytes showed increased tonofibrils and no structures suggestive of tyrosine crystals. Cytosol and mitochondrial tyrosine aminotransferase (TAT) activities of the liver were greatly decreased, while p -hydroxyphenyl pyruvate oxidase ( p -HPPO) activity was not decreased. The plasma tyrosine levels were controlled for 3 years with low phenylalanine-tyrosine diet.

Thirty-one patients with Bowen's disease were studied in a restricted district of Namikata and its neighborhood of Ehime, Japan. Nineteen were alive and 12 were dead; the youngest living patient was 52 years of age. Invasive skin cancers were found in 10 patients and internal malignancies in 10, including 7 patients with pulmonary cancers. Palmoplantar keratosis was present in 25 patients and raindrop-type pigment anomalies in 15. Neutron activation analysis of hair showed only slightly higher arsenic values in patients with Bowen's disease than those in normal controls, though the differences were statistically significant at p less than 0.05. A possible arsenic exposure 43 years previously was considered responsible for the occurrence of neoplasms, though the arsenic route and amount were not determined. Bowen's disease started within 10 years, invasive skin cancers after 20 years, and pulmonary cancers after 30 years following the suspected arsenic exposure.

A 26-year-old woman developed a verrucous papule on the dorsum of the right hand during the treatment of housewive’s hand dermatitis. Histological and ultrastructural study showed a typical appearance of Pagetoid reticulosis (Woringer-Kolopp disease).

Bilateral axillary and genital Paget's disease occurred in a 77-year-old man. All three lesions were histologically confirmed. Both axillary lesions were surgically excised and the genital lesion was subjected to topical chemotherapy with 5% fluorouracil cream under occlusion. The therapy was only partially successful because the reepithelializing follicular or apocrine duct epithelium contained the Paget's cells. The remaining lesion was treated with radiation. Simultaneous occurrence of Paget's disease in more than two separate regions appears quite exceptional.