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

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 GaInN quantumwells 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 spectroscopic methods. We found a strongly facet dependent growth mechanism leading to very flat surfaces on f1101g facets as opposed to their f1122g counterparts. An increased indium uptake on semipolar f1101g 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.