In this letter, InGaN-based solar cells with a p-InGaN/i-InGaN/n-GaN double-heterojunction structure were fabricated and characterized. Two kinds of sapphire substrates [i.e., a conventional sapphire substrate (CSS) and a patterned sapphire substrate (PSS)] were used for epitaxial growth. Both the solar cells grown on the CSS and the PSS demonstrated a high open-circuit voltage of 2.05 and 2.08 V, respectively. However, the short-circuit current of the solar cells grown on the PSS showed an improvement of 27.6% compared with that of the cells grown on the CSS. Such observation could be attributed to low edgedislocation density and the increase in the light-absorption path by the scattering of interface incident light between the substrate and the epitaxial layer for the solar cell grown on the PSS

A new coumarin derivative with blue-violet light absorption was designed and synthesized. Its structure was characterized based on elemental analysis, MS, and 1 H-NMR spectra. The absorption properties and thermal stability of the coumarin derivative were discussed. A sample disk, which was made by a spin-coated coumarin derivative recording layer, showed good recording and readout characteristics with CNR of about 45 dB for 8T carrier signals. These results show that the coumarin derivative dye is a promising candidate for optical recording using the wavelength of 405 nm.Index Terms-Blue-violet laser, coumarin derivative, high density digital versatile disk-recordable (HD DVD-R), organic dye.

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In this letter, we report on the fabrication and photovoltaic characteristics of p-i-n GaN/InGaN thin-film solar cells. The thin-film solar cells were fabricated by removing sapphire using a laser lift-off technique and, then, transferring the remaining p-i-n structure onto a Ti/Ag mirror-coated Si substrate via wafer bonding. The mirror structure is helpful to enhance light absorption for a solar cell with a thin absorption layer. After the thin-film process for a conventional sapphire-based p-i-n solar cell, the device exhibits an enhancement factor of 57.6% in current density and an increment in conversion efficiency from 0.55% to 0.80%. The physical origin for the photocurrent enhancement in the thin-film solar cell is related to multireflection of light by the mirror structure

Textured n-GaN/i-InGaN/p-GaN solar cells with interdigitated imbedded electrodes (IIEs) eliminating the electrode-shading loss have been investigated. In the absence of the electrode-shading effect, the optimized textured solar cell exhibits a conversion efficiency of 1.03%, which is 78% and 47% higher than those of the conventional structure and the structure with mirror coated on silicon substrate with electrode shading, respectively. The short-circuit current density of this textured IIE device is about 0.65 mA/cm(2), which is 71% and 44% higher than those of the two compared structures, respectively