Polarization anisotropy in the electroluminescence of m-plane InGaN-GaN multiple-quantum-well light-emitting diodes

InGaN-GaN multiple-quantum-well light-emitting diodes were fabricated on (10 (1) over bar0) m plane GaN films grown on (10 (1) over bar0) m plane 4H-SiC substrates. The [0001] axis of the epitaxial film is parallel to the [0001] axis of the substrate. The surface is striated, with features running perpendicular to the c axis and a maximum surface height difference of 45 nm. Electroluminescence shows strong polarization anisotropy, with 7x more light emitted with polarization perpendicular to the c axis compared to parallel to the c axis. An Ahrrenius fit of the polarization ratio indicates that there is a 49 meV difference in the energy gap between the two polarization states. This suggests that a high polarization ratio can be maintained at the high temperatures (>150 degrees C) and drive current densities required for high-power light-emitting diode applications. (C) 2005 American Institute of Physics.