Effect of chip size and ITO thickness on Micro LED performance

Abstract

Micro-LED is regarded as a new type of display panel technology with its advantages of high luminous efficiency, fast response speed, and high contrast. ITO film has been used widely in optoelectronic devices due to its low resistivity, high light transmittance, and good adhesion to the substrate. In this paper, Micro-LEDs with ITO thickness of 50nm and 110nm are designed and prepared. The size of Micro-LED is 40, 60, 80, 100µm, respectively. The performance of those Micro-LED was tested and analyzed. The result show that the thicker of ITO, has the smaller series resistance, and the smaller specific contact resistivity of P-GaN and ITO; when the current is low, ITO thickness is negatively correlated with the optical properties of Micro LED, while when the current is high, ITO thickness is positively correlated with the optical properties of Micro LED. For the 60um Micro LED, sample with 50nm ITO compared with that of 110nm ITO, the optical output power and luminous efficiency increased by 8.2% and 20.5% at current density is 278.89 A/cm2, but decreased by 10.33% and 7.3% at the current density 1666.67 A/cm2. In terms of heat, the thicker the ITO, the smaller the K factor, and the better thermal stability of Micro-LED.