GalnN-based LED structures on selectively grown semi-polar crystal facets

摘要

In conventional nitride-based light emitting diodes, huge internal electric fields lead to a reduced overlap of electron and hole wave functions in the active GalnN quantum wells as a consequence of the piezoelectricity of these polar materials. In order to minimize these internal fields while still maintaining the well-established c-direction as main epitaxial growth direction for high-quality low-defect-density layers, we have investigated semi-polar LED structures on the side-facets of triangular GaN stripes grown by selective area epitaxy. The reduced internal electric field could be confirmed by several spectro-scopic methods. We found a strongly facet dependent growth mechanism leading to very flat surfaces on {1101} facets as opposed to their {1122} counterparts. An increased indium uptake on semipolar { HOI} facets as compared to conventional c-plane layers helped to shift the LED.emission to longer wave lengths beyond 500 nm in the green spectral range despite the significantly reduced field-dependent Stark shift.