Enhanced Radiative Efficiency of InGaAs/GaAsP Multiple Quantum Wells by Optimizing the Thickness of Interlayers

InGaAs/GaAsP multiple quantum wells (MQWs) are used in electronic devices because the high radiative efficiency of MQWs improves the device performance. To realize high radiative efficiency, a GaAs interlayer is inserted to decrease the defects at the heterointerface between the well and barrier of the MQWs. However, it is unclear how the interlayer thickness and insertion position affect the radiative efficiency of the MQWs. Herein, the influence of the GaAs interlayer thickness on the radiative efficiency by measuring the photoluminescence of MQWs with different interlayer thicknesses is investigated. A thicker GaAs interlayer below the InGaAs enhances the radiative efficiency. Moreover, the GaAs interlayer above the InGaAs must be thicker than ≈6 nm to enhance the radiative efficiency. The initial growth of GaAs above the InGaAs degrades the surface morphology, which may be associated with the carry‐over of indium on the InGaAs surface and may generate defects between the InGaAs and GaAsP layers. The surface of sufficiently thick GaAs interlayers has a flatter morphology and is free from the degradation of radiative efficiency. The results suggest inserting of interlayers with a smooth surface morphology between strained layers during epitaxial growth is an effective method to suppress nonradiative recombination.