Wafer-scale organic-on-III-V monolithic heterogeneous integration for active-matrix micro-LED displays

Abstract

The organic thin-film transistor is advantageous for monolithic three-dimensional integration attributed to low temperature and facile solution processing. However, the electrical properties of solution deposited organic semiconductor channels are very sensitive to the substrate surface and processing conditions. An organic-last integration technology is developed for wafer-scale heterogeneous integration of a multi-layer organic material stack from solution onto the non-even substrate surface of a III-V micro light emitting diode plane. A via process is proposed to make the via interconnection after fabrication of the organic thin-film transistor. Low-defect uniform organic semiconductor and dielectric layers can then be formed on top to achieve high-quality interfaces. The resulting organic thin-film transistors exhibit superior performance for driving micro light emitting diode displays, in terms of milliampere driving current, and large ON/OFF current ratio approaching 1010 with excellent uniformity and reliability. Active-matrix micro light emitting diode displays are demonstrated with highest brightness of 150,000 nits and highest resolution of 254 pixels-per-inch.

The path to low temperature crack-free high refractive index inorganic thin films

“…This layer safeguards MicroLEDs from external factors like moisture and oxygen, ensuring long-term stability and performance. While traditional organic encapsulation layers offer good protection, their limitation to low refractive index values limits the efficiency of MicroLEDs [9]. On the other hand, hybrid materials (combine high refractive index inorganic nanoparticles like ZrO2 or TiO2 with organic polymers) suffer from high haze due to scattering caused by an index mismatch between the high-index nanoparticles and the low-index organic polymer.…”

An active‐matrix microLED display based on monolithic integration with IGZO backplane

“…Since such a strategy obviates the need for reliable, highthroughput release-transfer-bond or flip-chip processes, it can potentially improve display-level yield and increase manufacturing throughput. 1 In this work, we present a method of achieving true monolithic integration of microLEDs with a TFT backplane to fabricate a microdisplay. To accomplish this, we pattern microLEDs on a GaN-on-sapphire epitaxial wafer, deposit a passivation layer, and then fabricate IGZO TFTs on the top surface to serve as the activematrix backplane.…”

“…Finally, there is monolithic integration, that is, fabrication of the microLEDs and backplane TFTs on the same substrate. Since such a strategy obviates the need for reliable, high‐throughput release‐transfer‐bond or flip‐chip processes, it can potentially improve display‐level yield and increase manufacturing throughput 1 …”

“…Monolithic displays with various backplane technologies, such as organic thin-film transistors (TFTs) and amorphous oxide TFTs, have been reported in the literature. 1,2 Herein, we expand on the work performed by Yang et al, 2 which demonstrated the first monolithically integrated LED display with an indium gallium zinc oxide (IGZO) backplane by fabricating a similar device and performing a more comprehensive system-level performance characterization.…”

Advancements in Micro-LED Performance through Nanomaterials and Nanostructures: A Review

“…Factors such as epitaxial transfer [ 5 , 6 , 7 ], defect management [ 8 , 9 ], and bonding technology [ 10 , 11 ] leading to high manufacturing costs are the main reasons hindering its commercialization. Among them, the low external quantum efficiency (EQE) of μLEDs [ 12 , 13 , 14 ] and achieving full-color display [ 15 , 16 , 17 , 18 ] are among the main factors affecting its commercialization. In this paper, we discuss the main factors affecting the low EQE and luminous efficiency of μLED, as well as the low color conversion efficiency (CCE) of quantum dot (QD)-based μLEDs.…”