Quantitative analysis of leakage current in III-nitride micro-light-emitting diodes

The electrical characteristics under forward- and reverse-bias conditions of III-nitride blue and green micro-light-emitting diodes (mu LEDs) are analyzed. A fitting model is proposed to determine the contributions of reverse leakage current and the effectiveness of sidewall treatments. Moreover, the forward-bias currents of the mu LEDs are examined using the extracted ideality factor to examine the impacts of sidewall defects. The results show that sidewall treatments are highly effective for suppression of leakage currents. From the efficiency perspective, higher wall-plug efficiency (WPE) than external quantum efficiency (EQE) is observed when the operating voltage is lower than the photon voltage in both blue and green 20 x 20 mu m(2) devices. This enhancement of the WPE over the EQE is due to the suppression of Shockley-Read-Hall (SRH) nonradiative recombination. These observations indicate that mu LEDs with sidewall treatments not only improve optical performance but also further enhance the electrical performance of devices by suppressing the leakage current paths due to SRH nonradiative recombination processes.