| 초록 |
Integration of full-color-spectrum light emitter arrays in a compact chip-scale is required for many device applications, such as display, lighting, biosensors, and optogenetics. Among various candidates, indium gallium nitride (InGaN) based light-emitting diodes (LEDs) can have many advantages because of their high brightness and low power consumption, which are already conventionally available for blue and white light sources. Nevertheless, typical InGaN LEDs have homogeneous and uniform compositions of the InGaN quantum wells (QWs), exhibiting a monochromatic light emission with a narrow width of wavelength. To resolve the difficulty to integrate different color LEDs using a conventional InGaN QW structure, a method to engineer the local strains in the QW layers was employed. Using lithography and top-down etching procedures, thin film LEDs can be fabricated into arrays of nanopillar LEDs with various diameters. In this case, the strains in QWs can be gradually relaxed as decreasing the nanopillar diameter, yielding emission color changes. The electrical performance of the nanostructured active region was shown to be comparable to a conventional thin-film LED. The emission wavelength of the nanopillar LED was shown to be controlled by the nanopillar diameter following a simple hyperbolic function. Furthermore, additive color mixing across the visible spectrum was demonstrated from the LED pixel comprising of monolithically integrated, individually addressable red, green, and blue subpixels and the color control was characterized. The local strain engineering technique was also employed to demonstrate the feasibility of full-color see-through displays which have been of great interests, especially for augmented reality applications. |
