Correlation between photoluminescence and electroluminescence in GaN-related micro light emitting diodes: Effects of leakage current, applied bias, incident light absorption and carrier escape

Abstract

Accurately predicting the peak wavelength and intensity of the electroluminescence spectrum through the photoluminescence method which can be measured without connecting electrodes is not only practically important for the development of micro-LEDs that cannot be fully inspected for device development, but there is also a fundamental importance in understanding the light emitting mechanism of the LEDs. In this study, the correlation and detailed mechanism between PL and EL are systematically analyzed by considering the effects of carrier escape, carrier accumulation, applied bias, leakage current, incident light wavelength and light absorption in order to provide a clear path for all-optical inspection of light emitting diodes and complete understanding of the luminescence mechanism in GaN-related quantum wells. • To correlate the photoluminescence to the electroluminescence in GaN-related micro LEDs, detailed mechanism of PL and EL are systematically analyzed. • Direct experimental results on the sequential depletion process and on the wavefunction overlap in an individual quantum well were obtained. • In order to correlate the PL with EL, matching the concentration of carriers participating in recombination in both measurements is important. • Effect of carrier leakage plays an important role in EL in micro-LEDs which operates just above the turn on voltages. • Simultaneous excitation of 325 nm and 405 nm lasers can provide most similar carrier distribution as in EL by injecting carriers both in QWs and p-GaN.