Abstract
The mechanism of carrier recombination in downsized μ-LED chips from 100 × 100 to 10 × 10 μm2 on emission performance was systemically investigated. All photolithography processes for defining the μ-LED pattern were achieved by using a laser direct writing technique. This maskless technology achieved the glass-mask-free process, which not only can improve the exposure accuracy but also save the development time. The multi-functional SiO2 film as a passivation layer successfully reduced the leakage current density of μ-LED chips compared with the μ-LED chips without passivation layer. As decreasing the chip size to 10 × 10 μm2, the smallest chip size exhibited the highest ideality factor, which indicated the main carrier recombination at the high-defect-density zone in μ-LED chip leading to the decreased emission performance. The blue-shift phenomenon in the electroluminescence spectrum with decreasing the μ-LED chip size was due to the carrier screening effect and the band filling effect. The 10 × 10 μm2 μ-LED chip exhibited high EQE values in the high current density region with a less efficiency droop, and the max-EQE value was 18.8%. The luminance of 96 × 48 μ-LED array with the chip size of 20 × 20 μm2 exhibited a high value of 516 nits at the voltage of 3 V.
Highlights
The mechanism of carrier recombination in downsized μ-light-emitting diode (LED) chips from 100 × 100 to 10 × 10 μm[2] on emission performance was systemically investigated
For reducing the leakage current from the sidewall defects of μ-LED chips, the SiO2 passivation layer was deposited on the μ-LED chips after the MESA step by using plasma-enhanced chemical vapor deposition (PECVD)
The passivating step in the fabrication process of μ-LED chips was performed after the isolation step, the S iO2 passivation layer was deposited after the MESA step for analyzing the effect of passivated ability via a single dry etching process
Summary
The mechanism of carrier recombination in downsized μ-LED chips from 100 × 100 to 10 × 10 μm[2] on emission performance was systemically investigated. All photolithography processes for defining the μ-LED pattern were achieved by using a laser direct writing technique. The photolithography processes for defining the μ-LED pattern were achieved by using a laser direct writing technique. This system can reduce the use of glass masks, and can improve the exposure accuracy and save the development time. The performance of μ-LED array with a 20 × 20 μm[2] chip size was studied
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