Optical properties of a novel parabolic quantum well structure in InGaN/GaN light emitters

We theoretically investigate the optical properties of conventional, normal (type A) parabolic and novel (type B) parabolic InGaN quantum well (QW) for blue light emitters. Two specially designed active layer structures by parabolic-shaped QW are proposed, and the optical characteristics of these two parabolic QW structures are calculated and compared to those of conventional QW structures. The electron-hole wavefunction overlap ((e-hh)) of type-B parabolic QWs is 2.8 times (69.6%) that in the conventional QW (24.8%), and the spontaneous emission rate is ninefold that of conventional QWs. The transparency carrier density of type-B parabolic QWs is much smaller than type-A parabolic or conventional QW. These results can be attributed to a higher indium index in the center of the type-B parabolic QWs, and that leads to better confinement of carriers wavefunctions.