High quality GaN microplatelets grown by metal-organic vapor phase epitaxy on patterned silicon-on-insulator substrates: Toward micro light-emitting diodes

In this paper, we report the use of three pendeo-epitaxy growth approaches as a way of reducing the threading dislocation density (TDD) of 20 x 20 mu m(2) GaN platelets to be used for the development of micro light-emitting diodes (mu LEDs). The method relies on the coalescence of GaN crystallites grown on top of a network of deformable pillars etched into a silicon-on-insulator substrate. Our approach takes advantage of the creeping properties of SiO2 at the usual GaN epitaxial growth temperature, allowing the GaN crystallites to align and reduce the grain boundary dislocations. Furthermore, this bottom-up approach allows to get rid of the dry plasma etching step for mu LEDs fabrication, which highly deteriorates sidewalls, reducing the efficiency of future displays. By optimizing the growth conditions and inducing asymmetric nucleation, a TDD of 2.5 x 10(8) cm(-2) has been achieved on the GaN platelets, while keeping a smooth surface.