Photoluminescence Properties of InGaN/InGaN MQWs with Different Electron Injection Layers

The structural and optical properties of InxGa1-xN/InyGa1-yN multi quantum well (MQW) light emitting devices with/without electron injection layers were studied. The samples with electron injection layer consist of step-graded (GIE) and two step staircase (SEI) electron injection layer between n-type GaN and MQWs active region. Edge and screw type of dislocation densities were deduced from High Resolution X-Ray Diffraction (HR-XRD) curves and no significant difference were realized. The zeroth and higher order satellite peaks were more clearly observed in the sample without electron injection layer. Optical characterization was carried out by temperature dependent photoluminescence (PL) technique. It was found that the PL densities of samples with step-graded and two step-staircase electron injection layers had almost two times lower temperature dependence compared to the reference sample without electron injection layer. On the other hand, the line width of the photoluminescence peak associated with MQWs is much narrower at low temperature for sample without electron injection layer than the other two samples.