12th International Conference on Optics, Photonics & Lasers
Xiamen University, China
Title: Abnormal radiative interband transitions and tailorable orbital-state coupling in High- Al-Content AlGaN quantum wells
Biography: Junyong Kang
It is widely held that the confinement of carriers at lowest quantum level is more pronounced than that of higher quantum levels, which has been long established on the conventional continuous potential wells and favourable for efficient light emission. We observed the abnormal behavior of the carrier confinement from the c-plane of high-Alcontent AlGaN quantum well (QW) due to the dispersive crystal field split-off hole composed of pz orbitals. [ACS Photonics 4, 2197–2202 (2017)]. The orientational pz orbitals are sensitive to the confi ning directions which affect the orbital inter-coupling. The barrier potential for the confi nement is then determined by the joint effect of orbital inter-coupling and the band off set. We have performed theoretical calculations by constructing Al0.75Ga0.25N/ AlN quantum well models with variable lattice orientations to further investigate the orbital inter-coupling among atoms between the well and barrier regions. It is found that, the barrier potential as well as the transition rate of the band edge is enhanced by the orbital engineering with the well plane inclined from 0º to 90º with a step of 30º, referring to the (0001) plane. Experimentally, the concept of the orbital engineering is demonstrated through the construction of inclining well planes on the semi- and non-polar planes implemented in the micro-rods. The higher emission intensity from the QW on the non-polar plane is confirmed by localized cathodoluminescence (CL). The orbital engineering presented in this work aims to spur on the further improvement of high-Al-content AlGaN optoelectronic devices and the design of other innovative devices.