Influence of circuit parameters on the electroluminescence characteristics of single-contact-driven micro-LEDs

Abstract The continued miniaturization of micro-light-emitting-diodes (Micro-LEDs) presents huge challenges for chip yield testing by using electrical contact probes. As showing significant advantages in chip inspection with low damage, low technical requirements and high applicability, the single-contact driving method is emerging as a burgeoning research focus. However, the underlying mechanism of this driving mode remains poorly understood, particularly the lack of direct physical descriptions of the electroluminescence (EL) process and effective driving optimization strategies of micro-LEDs. Herein, finite element simulation is applied to quantitatively explore and analyze the intrinsic effects of circuit parameters on the EL characteristics of single-contact-driven micro-LEDs (SCD micro-LEDs), including driving waveform, amplitude, frequency and the capacitance value of sapphire substrate. Through comparison with experimental results, increasing the amplitude of driving voltage and the capacitance value of sapphire substrate within a certain range, adjusting the frequency to an appropriate level and using the square wave are all conducive to achieve high stability and high efficiency of SCD micro-LEDs. Our work lays a theoretical foundation for the study of the operation mechanism of SCD micro-LEDs, which is expected to provide a certain guiding role for improving its EL characteristics and to promote the application of this mode in the field of chip detection.