Internal Quantum Efficiency of Whole-Composition-Range AlGaN Multiquantum Wells

We analyze the internal quantum efficiency (IQE) of whole-composition-range AlGaN multiquantum wells (MQWs) on AlGaN with various dislocation densities (DDs) by excitation-density-dependent photoluminescence measurement. IQEs of deep ultraviolet/ultraviolet (DUV/UV) MQWs are strongly dependent on the DD. IQE with an excess carrier density of $1\times 10^{18}$ cm -3 changes from 4 to 64% when the DD changes from $6\times 10^{9}$ to $2\times 10^{8}$ cm -2 . This trend is almost the same for DUV/UV MQWs with emission wavelength ranging from 230 to 350 nm. Thus, the reduction of the DD is very important for the realization of a high-IQE DUV/UV active layer.