GaInN/GaN LEDs auf semipolaren Seitenfacetten mittels selektiver Epitaxie hergestellter GaN-Streifen (English shop)

Preview

Table of Contents, Datei (58 KB)
Extract, Datei (47 KB)

LEDs emitting in the blue spectral range based on the AlGaInN material system have already been commercialised and are well established. Nevertheless, they still exhibit one disadvantage: the group-III nitride, which preferentially forms in the wurtzite structure, is polar along the c-direction, which has so far been the most commonly used direction for crystal deposition. Owing to the resulting piezoelectric field, this polarity has a negative effect on the optical output power and the efficiency, particularly with increasing In content and thicker quantum wells, as required for longer-wavelength emission (green spectral range).

In this work, such weakly polar crystal planes were fabricated by selective epitaxy as inclined side facets of GaN stripes with a triangular cross-section. The LED structure was subsequently deposited on these semi-polar crystal planes. After demonstrating the basic functionality of the LEDs, various investigations were carried out to verify the reduced piezoelectric field. These included, in particular, the comparison of the spectra with a regular LED on the polar c-plane using luminescence measurements with respect to the red shift caused by the quantum confined Stark effect, and the adaptation of the processing to the novel LED structures in order to examine an improved output power.