Investigation of a Separated Short-Wavelength Peak in InGaN Red Light-Emitting Diodes

1 min read · Thu, Sep 9 2021

The paper reports the investigation of the electroluminescence properties of the additional peak in the EL spectrum of InGaN-based red LED structure. These results were helpful for understanding the EL performance of the red InGaN QWs and may be useful as guidelines to improve the quality of high-In-content QWs in the future.

[Abstract] We fabricated indium gallium nitride (InGaN) red light-emitting diodes (LEDs) with a peak emission wavelength of 649 nm and investigated their electroluminescence (EL) properties. An additional separated peak in the EL spectrum of the red LEDs at 20 mA was observed at 465 nm. This additional peak also exhibits a blue-shift with increasing currents as does the main emission peak. Using high-resolution microscopy, we observed many point-like emission spots in the EL emission images at the currents below 1 mA. However, these emission spots cannot be identified at currents above 5 mA because the red emission from quantum wells (QWs) is much stronger than that emitted by these spots. Finally, we demonstrate that these emission spots are related to the defects generated in red QWs. The measured In content was lower at the vicinity of the defects, which was regarded as the reason for separated short-wavelength emission in red InGaN LEDs.