How to Make Semi‐Polar InGaN Light Emitting Diodes with High Internal Quantum Efficiency: The Importance of the Internal Field

Abstract

The theoretical expectation of semi‐polar light emitting diodes (LEDs) is reviewed and compared it to the experimental data. The reported peak internal quantum efficiency (IQE) of non‐polar, and semi‐polar InGaN LEDs are always much lower than the standard polar (0001) oriented LEDs. Calculating the band structure and states including the n‐ and p‐doped layer of LEDs in many orientations, It is found that the inverted polarization‐induced fields for most common semi‐polar orientations like (112) or (201) causes the hole ground state to leak out of the quantum well (QW) into the p‐doped GaN above and by this a low wavefunction overlap and a strongly increased probability for non‐radiative recombination with point defect outside the QW. Based on the calculations, (111), (102), or (103) are predicted as best candidates for LEDs with higher IQE at higher current densities than (0001). LEDs in the uncommon semi‐polar (103) orientation on sapphire have been realized. The (103) LEDs showed the same IQE as (0001) LEDs but at a much higher current density due to the higher overlap of electron and hole wave functions, which is especially useful for micro‐LEDs.