Temperature-Induced Stress Performance of High-Density GaN Micro-LED Arrays for Industrial Mass Production

The high-temperature-induced stress performance of GaN-based blue micro light emitting-diode (micro-LED) arrays with a pixel size of 5 × 5 μm2 (6 μm pitch) is studied, and monochrome micro-LED displays with 4233 PPI for industrial mass production are demonstrated. The temperature-induced stress performance of the micro-LED arrays with the same pixel size is evaluated under identical measurement conditions as a function of the temperature to observe the changes in optoelectronic performance before and after temperature-dependent electroluminescence (TDEL) measurements. The photoluminescence (PL) intensities of each pixel in a matrix (2 × 2 pixels) for site 1 (center), site 2 (near sidewall), and site 3 (sidewall) decreased after TDEL measurement, and the reduction rates of peak wavelength intensity at site 1, site 2, and site 3 are 31.37%, 62.95%, and 65.11%, respectively. In addition, the light distribution of the two pixels on the right is degraded after TDEL measurement because high-temperature measurement creates point defects at mesa-sidewalls that act as nonradiative recombination centers. However, the forward voltage (VF) variations for a single pixel and for 120 pixels in five different regions on a 4 in. wafer are only 0.02 V (0.72%) and 0.04 V (1.42%), respectively. The zoomed-in image of the passive matrix-type blue micro-LED arrays showing light emittance demonstrates good display uniformity and brightness simultaneously at 1710 pixels. The obtained results have important implications for the advancement and potential commercial viability of micro-LED displays, demonstrating their ability to meet stringent image quality standards in real-world applications.