Enhanced Optical Polarization of Nitride LEDs by Increased Indium Incorporation

In recent years, III-V nitride-based blue and green LEDs have begun to emerge in general lighting and full color display applications. Internal electrical polarization is a unique property of the (Al,In,Ga)N system. Since atoms in the III-V nitride system do not maintain their ideal positions, this polarization field almost always exists along the c-axis, making the c-plane a polar plane. In contrast, III-V nitride-based LEDs conventionally grown on the c-plane show negligible light polarization.

Researchers at the University of California, Santa Barbara have developed a novel technique to obtain high polarization ratios from nonpolar LEDs, thereby improving performance. The present invention accomplishes higher polarization ratios in electroluminescence from nonpolar LEDs by increasing the indium content in light-emitting layers. A possible modification of this invention is to introduce strain controlling layers in the LED structure, which results in increased polarization ratios. The present invention requires no extra process in material growths, clean room processing, or device packaging.