Semipolar-Based Yellow, Green, Blue LEDs with Improved Performance

Conventional nitride technology for electronic and optoelectronic devices employs nitride films grown along the polar c-direction. However, conventional structures in III-nitride based optoelectronic and electronic devices suffer from the undesirable quantum-confined Stark effect (QCSE), due to the existence of strong piezoelectric and spontaneous polarizations. One approach to eliminating the polarization effects in devices is to grow the devices on nonpolar planes of the crystal. Unfortunately, growth on nonpolar nitrides remains challenging and has not yet been widely adopted in the III-nitride industry.

Researchers at the University of California, Santa Barbara have developed a novel approach to reducing or possibly eliminating the polarization effects in GaN-based optoelectronic devices. This approach includes growing the devices on semipolar planes of the crystal. Using semipolar planes instead of c-plane nitrides will reduce total polarization, and there may even be zero polarization for specific alloy compositions. Reducing the polarization field allows for the growth of thicker quantum wells. With thicker quantum wells, higher Indium composition and thus longer wavelength emission can be achieved. The novel approach allows for the fabrication of blue, green, and yellow LEDs on semipolar (Al, In, Ga, B)N semiconductor crystals.