Polarization Self-Screened Multiple Quantum Wells for Deep Ultraviolet Light-Emitting Diodes to Enhance the Optical Power

We experimentally and numerically propose a deep ultraviolet light-emitting diode (DUV LED) possessing the quantum barriers (QBs) with the gradually reduced Al composition along the [0001] orientation. The induced negative polarization bulk charges in the graded QBs can screen the positive polarization sheet charges at the QB/quantum well (QW) interface, i.e., generating the polarization self-screening effect, which weakens the electric field in the QWs. The polarization self-screened feature is important in enhancing the overlap level of the electron and hole wave functions within the active region and increasing the hole injection, thus improving the electroluminescence intensity and the optical power.