Optical response from lenslike semiconductor nipple arrays

Abstract

The authors reported the use of recessive size reduction in self-assembled polystyrene sphere mask with anisotropic etching to form lenslike nipple arrays onto the surface of silicon and gallium nitride. These devices are shown to exhibit a filling factor near to an ideal close-packed condition and paraboloidlike etch profile with slope increased proportionally to the device aspect ratio. Specular reflectivity of less than 3% was observed over the visible spectral range for the 0.35-μm-period nipple-lens arrays. Using two-dimensional rigorous coupled-wave analysis, the latter phenomenon can be ascribed to a gradual index matching mechanism accessed by a high surface-coverage semiconductor nipple array structure.

Self-Assembled Two-Dimensional Surface Structures for Beam Shaping of GaN-Based Vertical-Injection Light-Emitting Diodes

“…The respective output powers for VI-LEDs with a flat surface and with self-assembled biomimetic surface structures were 143 and 241 mW at a driving current of 350 mA, showing an enhancement factor of 68%. The light output power increment arises from both the roughened surface and also the gradient changed refractive index due to the biomimetic structural profile [17].…”

Antireflective surfaces based on biomimetic nanopillared arrays

“…To generate ARS surfaces on silicon [31,32,56] and other semiconductors [28,57], several simple approaches based on colloidal lithography have been reported. However, their antireflective properties are suboptimal due to low aspect ratio of the ARS arrays, because it is difficult to prepare ARS arrays with aspect ratio above 10 using colloidal lithography.…”

Angle-resolved reflectance spectroscopy of passivated trapezoidcorn nanostructures for crystalline silicon photovoltaics

“…Several studies of sub-micrometer gratings (SMG) on c-Si surface have shown ultra-low reflectivity at normal incidence and low reflectivity at large angles of incidence (AOI) was also demonstrated with a single wavelength [2][3][4][5]. The previous researches have shown that sharp nanostructures such as nano-cones or pyramids, exhibit broadband antireflective properties at normal incidence and large AOI [6][7][8][9]. However, sharp nano-tips may not be preferred in photovoltaics as they substantially result in considerable surface states that trap photo-generated carriers and also increase challenges in making ohmic contacts for electrodes.…”