P-Down InGaN/GaN Multiple Quantum Wells Light-Emitting Diode Structure Grown by Metal-Organic Vapor-Phase Epitaxy

An inverted or p-down InGaN/GaN multiple quantum wells light-emitting diode structure is studied. The crystalline quality of the quantum wells is comparable to that of the n-down structure by using a Si or In co-doped GaN:Mg layer underneath the active layer. I-V characteristics can be improved by insertion of a tunnel layer, either a 3D growth GaN:Mg layer or an AlGaN/GaN superlattice layer. The feasibility of such a structure for practical application is also evaluated by luminescence measurement. 6 refs.