A high-performance light-trapping structure for Si was fabricated with an etching margin of only >1 µm using Ge islands grown by gas-source molecular beam epitaxy as etching masks. KOH solution containing isopropyl alcohol and HF + H 2 O 2 + CH 3 COOH mixed solution were used as etchants. The reflectance of the structure was shown to be comparable to that of a conventional pyramid texture, which requires a larger etching margin of >10 µm. In addition, a potential short-circuit current density (p-J sc ) of 42.3 mA/cm 2 was obtained for the sample after the deposition of indium tin oxide, which confirms that the light-trapping structure is applicable to crystalline Si solar cells with thinner wafers.

The upper and lower limits of the excitation function of the (63)Cu(n,p)(63)Ni reaction were experimentally determined, and the number of (63)Ni nuclei produced in copper samples exposed to atomic bomb neutrons in Hiroshima was estimated by using the experimental excitation functions and the neutron fluences given in the DS02 dosimetry system. The estimated number of (63)Ni nuclei was compared with that measured and with that calculated using the DS02 dosimetry system and the corresponding ENDF/B-VI cross section. In comparison with DS02, there is about a 60% maximum difference in (63)Ni production at the hypocenter when the experimental upper cross section values are used. The difference becomes smaller at greater distances from the hypocenter and decreases, for example, to less than 30 and 5% when using the upper and lower experimental cross sections at 1,000 m, respectively.

The impact of the size distributions of Ge islands on the structural and optical characteristics of anti-reflection structures was investigated. The variation of island size distribution was achieved through the variation of growth temperature in gas-source molecular beam epitaxy at 700 °C-800 °C. Ge islands were utilized as etching masks to form the anti-reflection structures. By using lower growth temperature of 700 °C and subsequent etching, larger texture without many hollows was formed in contrast to that using 800 °C. Broader size distribution of islands formed at 700 °C was found to lead to larger texture size. Smaller texture is formed by smaller islands and short etching, whereas larger texture is formed by erosion of smaller texture during long etching. A potential short-circuit current density of 36.75 mA cm −2 was obtained for the sample by the islands grown at 700 °C with reduced etching margins, comparable to that of conventional pyramid textures.

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