Preparation method of polystyrene semispheres used as microlenses for improving LED light outlet efficiency

Abstract

The invention provides a preparation method of polystyrene semispheres used as microlenses for improving the LED light outlet efficiency, which comprises the following steps: (1) sequentially and epitaxially growing an N-shaped contact layer, a multiquantum well region active region and a P-shaped contact layer on a substrate by a conventional method for growing LED epitaxial wafers by MOCVD, and forming an epitaxial wafer; (2) preparing a P electrode, an N electrode and a semi-cut region on the epitaxial wafer according to a conventional process; (3) paving a layer of single-layer film formed by the polystyrene spheres through tight distribution on one side of the P electrode on the processed epitaxial wafer, wherein the diameter of the polystyrene spheres is between 100 nm and 1 mum; and (4) baking the epitaxial wafer paved with the PS spheres for 5 to 60 seconds at 110 DEG C to 120 DEG C, cooling the epitaxial wafers to the room temperature in 5 to 10 seconds, and obtaining the polystyrene semispheres in periodic distribution. The invention uses the single-layer film with the polystyrene sphere distribution to obtain periodic arrays of the PS semispheres through baking, and the polystyrene semispheres are used as the microlenses for improving the LED light outlet efficiency, and the invention has the characteristics of low cost, simplicity, easy implementation, high controllability and good uniformity, and can realize the periodic distribution.

Description

technical field [0001] The invention relates to a method for improving the light-emitting efficiency of LEDs by using polystyrene (PS) hemispheres as microlenses, and belongs to the technical field of light-emitting diode manufacture. Background technique [0002] LED has the advantages of long luminous life, high reliability, environmental friendliness, small size, fast response, etc., and is increasingly used in information display, image processing, and lighting optical systems. With the development of semiconductor technology and the emergence of high-power LEDs, the power of LEDs is constantly increasing, but there is still a lot of room for improvement in terms of photoelectric conversion efficiency. [0003] There are generally two ways to improve LED efficiency, one is to improve the internal quantum efficiency of LED, which is related to the quality and structure of the epitaxial wafer; the second way is to improve the light extraction efficiency. The internal quan...

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Problems solved by technology

For example, in 2007, Ming-Kwei Lee et al. used focused ion beam etching to prepare a periodic array structure of microlenses on the sapphire substrate of an inverted GaN-based LED (APPLIED PHYSICS LETTERS 91, 051111 (2007)), However, this method has the disadvantages of expensive equipment, easy to introduce damage to the surface, requires a mask, and is difficult to achieve a nanoscale structure; in 2008, they used the liquid phase deposition method to prepare submicron-sized silicon dioxide on the surface of the blue LED. The hemispherical structure, as a microlens, increases the efficiency of light output (APPLIED PHYSICS LETTERS 92, 061103 (2008)), but this method has the disadvantages of small silica hemisphere coverage, disorderly arrangement, and non-periodicity.

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