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Optical sectioning structured illumination microscopy (OS-SIM) provides optical sectioning capability in wide-field microscopy. The required illumination patterns have traditionally been generated using spatial light modulators (SLM), laser interference patterns, or digital micromirror devices (DMDs) which are too complex to implement in miniscope systems. MicroLEDs have emerged as an alternative light source for patterned illumination due to their extreme brightness capability and small emitter sizes. This paper presents a directly addressable striped microLED microdisplay with 100 rows on a flexible cable (70 cm long) for use as an OS-SIM light source in a benchtop setup. The overall design of the microdisplay is described in detail with luminance-current-voltage characterization. OS-SIM implementation with a benchtop setup shows the optical sectioning capability of the system by imaging within a 500 µm thick fixed brain slice from a transgenic mouse where oligodendrocytes are labeled with a green fluorescent protein (GFP). Results show improved contrast in reconstructed optically sectioned images of 86.92% (OS-SIM) compared with 44.31% (pseudo-widefield). MicroLED based OS-SIM therefore offers a new capability for deep tissue widefield imaging. 

Micro light-emitting diode (microLED) structures were modeled and validated with fabricated devices to investigate p-type GaN (pGaN) contact size dependence on power output efficiency. Two schemes were investigated: a constant 10μm diameter pGaN contact and varying microLED sizes and a constant 10μm diameter microLED with varying contact sizes. Modeled devices show a 17% improvement in output power by increasing the microLED die size. Fabricated devices followed the same trend with a 70% improvement in power output. Modeled microLED devices of a constant size and varying inner contact sizes show optimized power output at different current densities for various contact sizes. In particular, lower current densities show optimized output for smaller pGaN contacts and trend towards larger contacts for higher current densities in a balance between undesirable efficiency losses at high-current injection and preventing surface recombination losses. We show that for all device geometries, it is preferential to shrink the pGaN contact to maximize efficiency by suppressing surface recombination losses and further improvements should be carefully considered to optimize efficiency for a desired operational brightness. 

Abstract Ultrahigh‐resolution micro light‐emitting diode (LED) displays are emerging as a viable technology for self‐emissive displays. Several of the critical issues facing micro LED displays with millions of pixels are fidelity, process control, and defect analysis during LED fabrication and transfer. Here, we investigate two non‐destructive test methods, photoluminescent and cathodoluminescent imaging, and compare them with electroluminescent images to verify LED fidelity and evaluate these methods as potential tools for defect analysis. We show that utilizing cathodoluminescent imaging as an analysis tool provides a rich data set that can identify and categorize common defects during micro LED display fabrication that correspond to electroluminescence. Photoluminescent imaging, however, is not an effective method for fidelity analysis but does provide information on dry‐etching uniformity.