Green Semipolar ($11overline{2}2$) InGaN Micro-Light-Emitting-Diodes on ($11overline{2}2$) GaN/Sapphire Template

摘要

In this work, we fabricated five different sizes of 520 nm semipolar micro-light-emitting-diodes ($mu ext{LEDs}$), ranging from 100×100 to $20imes 20mu mathrm{m}^{2}$, on (11–22) GaN/sapphire template. Based upon the results from atom probe tomography (APT), no InGaN cluster was observed in the active region. For the current-voltage characteristics, the voltages were 3.2 V and 3.0 V at 60 A/cm^{2 for the 100×100 and $20imes 20 mu mathrm{m}^{2} mu ext{LEDs}$, respectively. In terms of the optical aspect, the $20imes 20mu mathrm{m}^{2}mu ext{LED}$ demonstrated a trivial blue-shift of 9 nm as the inject current density increases from 5 A/cm2 to 100 A/cm2. Moreover, for the external quantum efficiency (EQE) performances, $mu ext{LEDs}$ in all sizes yielded 6-8% efficiency droop between the peak EQE current density and at 100 A/cm2, and the peak EQE was 2% for all $mu ext{LED}$ sizes. Although further improvements on growth and materials are required for better $mu ext{LED}$ performances, this demonstration revealed the feasibility to produce long-wavelength semipolar InGaN $mu ext{LEDs}$ with high efficiency on large-area sapphire substrates.}