Lehigh University

Pisist Kumnorkaew

Nelson Tansu

James F Gilchrist

Hongping Zhao

Guangyu Liu

Yik-Khoon Ee

Xiaohang Li

A conventional semiconductor LED is modified to include a microlens layer over its light-emitting surface. The LED may have an active layer including at least one quantum well layer of InGaN and GaN. The microlens layer includes a plurality of concave microstructures that cause light rays emanating from the LED to diffuse outwardly, leading to an increase in the light extraction efficiency of the LED. The concave microstructures may be arranged in a substantially uniform array, such as a close-packed hexagonal array. The microlens layer is preferably constructed of curable material, such as polydimethylsiloxane (PDMS), and is formed by soft-lithography imprinting by contacting fluid material of the microlens layer with a template bearing a monolayer of homogeneous microsphere crystals, to cause concave impressions, and then curing the material to fix the concave microstructures in the microlens layer and provide relatively uniform surface roughness.

Semiconductor light-emitting devices having concave microstructures providing improved light extraction efficiency and method for producing same

A III-Nitride semiconductor LED provides broadband light emission, across all or most of the visible light wavelength spectrum, and a method for producing same. The LED includes a polarization field management template that has a three-dimensional patterned surface. The surface may be patterned with an array of hemispherical cavities, which may be formed by growing the template around a temporary template layer of spherical or other crystals. The method involves growing a quantum well layer on the patterned surface. The topographical variations in the patterned surface of the template cause corresponding topographical variations in the quantum well layer. These variations in spatial orientation of portions of the quantum well layer cause the polarization field of the quantum well layer to vary across the surface of the LED, which leads to energy transition shifting that provides 'white' light emission across a broad wavelength spectrum.

Broadband light emitting diodes and method for producing same

Growing community of inventors

Bethlehem, PA, United States of America

Pisist Kumnorkaew