Towards green electroluminescence of semipolar InGaN-MQWs on GaN pyramids

InGaN-structures have attracted much interest due to their properties which allow the development of optoelectronic devices such as light emitting diodes (LEDs) and laser diodes. Recently, blue and green InGaN-LEDs are available, but the so-called quantum-confined Stark effect (QCSE) reduces the emission efficiency of these devices by bowing of the band structure. To lower the QCSE, hexagonal Si-doped GaN-pyramids were deposited, providing semipolar sidewalls tilted 62 with respect to the GaN c-plane. These planes are used for the deposition of InGaN-multiple quantum wells (MQWs). The whole structure is fabricated by low-pressure metal-organic vapor-phase epitaxy (MOVPE). Next to the structural characterization of the samples by scanning electron microscopy, photoluminescence techniques are used to reveal the optical properties. Besides these optical investigation of the Indium distribution on the pyramidal structures, p-i-n junctions are formed by placing a hole injection coating on top of the pyramids. Contact structures were developed to allow electrical injection and the examination of electroluminescence.