Effect of O Impurity on the Properties of InGaN/GaN Multiple Quantum Well and Light Emitting Diode Structures

InGaN/GaN multiple quantum well (MQW) and light emitting diode (LED) structures with different GaN barrier growth temperatures have been grown by metalorganic chemical vapor deposition (MOCVD). Atomic Force Microscopy (AFM)-Conductive AFM (CAFM) analysis has been performed to study the submicron scale structural and electrical properties of the LED structures. The effect of high O impurity concentration, introduced during the low temperature barrier layer growth, on the MQW LED structure has been explored. It is observed that (VGa-ON)2- point defects formed in the MQW layer serve as deep-level traps and lead to defect-assisted tunneling. Increasing barrier growth temperature decreases O impurity incorporation and thus improves the device performance.