Monolithic integration of individually addressable light-emitting diode (LED) color pixels is reported. The integration is enabled by local strain engineering. The use of a nanostructured active region comprising one or more nanopillars allows color tuning across the visible spectrum. In the current work, integration of amber, green, and blue pixels is demonstrated. The nanopillar LEDs exhibit an electrical performance comparable to that of a conventional thin-film LED fabricated on the same wafer. The proposed platform uses only standard epitaxy and a similar process flow as a conventional LED. It is also shown that the emission intensity can be linearly tuned without shifting the color coordinate of individual pixels.

Additive color mixing across the visible spectrum was demonstrated from an InGaN based light-emitting diode (LED) pixel comprising red, green, and blue subpixels monolithically integrated and enabled by local strain engineering. The device was fabricated using a top-down approach on a metal-organic chemical vapor deposition-grown sample consisting of a typical LED epitaxial stack. The three color subpixels were defined in a single lithographic step. The device was characterized for its electrical properties and emission spectra under an uncooled condition, which is desirable in practical applications. The color mixing was controlled by pulse-width modulation, and the degree of color control was also characterized.

A force sensor capable of detecting both the magnitude and direction of the shear stress is proposed and demonstrated. The structure is based on an array of gallium nitride (GaN) light-emitting nanostructures and an off-the-shelf imager. The directional sensitivity originates from symmetry breaking of the nanostructures. Only a common bias is required for all GaN elements, making two-dimensional mapping of the stress relatively simple. As the stress sensing relies only on differential measurements, no stringent uniformity requirement across the sensor array is necessary.

A set of empirical equations were developed to describe the optical properties of III-nitride dot-in-wire nanostructures. These equations depend only on the geometric properties of the structures, enabling the design process of a III-nitride light emitter comprised of dot-in-wire polar nanostructures, to be greatly simplified without first-principle calculations. Results from the empirical model were compared to experimental measurements and reasonably good agreements were observed. Strain relaxation was found to be the dominant effect in determining the optical properties of dot-in-wire nanostructures.