Influence of thermal treatment and electron-blocking layers on the optical properties of InGaP/InGaAlP MQW structures for red RCLEDs

We report the effects of rapid thermal annealing (RTA) and electron-blocking layers (EBL) on the optical properties of InGaP/InGaAlP multiple quantum well (MQW) structures for red resonant-cavity light-emitting diodes. The photoluminescence (PL) intensity is strongly dependent on the RTA temperature and time due to the annealing of non-radiative defect centers in QWs. The use of various EBL structures, such as p-InGaAlP, InAlP and p-InAlP, at the top and the top/bottom of MQWs increases the PL and electroluminescence (EL) intensities of InGaP/InGaAlP MQW structures by preventing electron overflow from the active region. For the as-grown sample with two EBLs of p-InAlP at the top/bottom of QWs, the PL intensity is approximately 14 times higher than that of the sample without an EBL. The additional RTA process at 720 °C for 240 s improves the PL intensity (i.e. 46 times) dramatically. For the device structure with two EBLs of p-InAlP on the annealed wafer, the EL intensity is improved by 12 times at 20 mA compared to the no-EBL structure.