Abstract: In a general aspect, a microLED display (600) includes a semiconductor member (605a) having a thickness, where the semiconductor member has a LED side (602a) configured to produce light (670) for displaying an image, and an output side (602b) configured to display the image by outputting the produced light, the output side being opposite the LED side. The display also includes a plurality of microLED mesas (627) included on the LED side of the semiconductor member, and a plurality of etched features (655a, 655b, 655c) defined in the semiconductor member. The plurality of etched features are defined on at least one of the LED side or the output side. The plurality of etched features define un-etched portions in the semiconductor member having respective thicknesses that are less than the thickness of the semiconductor member. The respective thicknesses of the un-etched portions are uniform across the display, with a total thickness variation less than 200 nanometers.

Abstract: Group III-V nitride semiconductors are used as optoelectronic light emitters. The semiconductor alloy InGaN is used as the active region in nitride laser diodes and LEDs, as its bandgap energy can be tuned by adjusting the alloy composition, to span the entire visible spectrum. InGaN layers of high-indium content, as required for blue or green emission are difficult to grow, however, because the poor lattice mismatch between GaN and InGaN causes alloy segregation. In this situation, the inhomogeneous alloy composition results in spectrally impure emission, and diminished optical gain. To suppress segregation, the high-indium-content InGaN active region may be deposited over a thick InGaN layer, substituted for the more typical GaN. First depositing a thick InGaN layer establishes a larger lattice parameter than that of GaN. Consequently, a high indium content heterostructure active region grown over the thick InGaN layer experiences significantly less lattice mismatch compared to GaN.