Prospective emission efficiency and in-plane light polarization of nonpolar m-plane In_xGa_(1-x)N/GaN blue light emitting diodes fabricated on freestanding GaN substrates

摘要

Prospective equivalent internal quantum efficiency (η_(int)) of approximately 34% at 300 K was demonstrated for the blue emission peak of nonpolar m-plane (1100) In_xGa_(1-x)N/GaN multiple quantum well light emitting diodes (LEDs) fabricated on freestanding m-plane GaN substrates. Although the η_(int) value is yet lower than that of conventional c-plane blue LEDs ( > 70%), the results encourage one to realize high performance green, amber, and red LEDs by reducing the concentration of nonradiative defects, according to the absence of the quantum-confined Stark effects due to the polarization fields parallel to the quantum well normal. The electric field component of the blue surface emission was polarized perpendicular to the c axis with the in-plane polarization ratio of 0.58 at 300 K.