Advances in nano-enabled GaN photonic devices

In this work, the results are presented of a nanorod LED array. If the lateral size of the nanorods is small enough, it is possible to achieve a degree of lateral confinement. If the nanorods are ordered into a suitable photonic lattice, then this will reduce the lateral spontaneous emission and enhance emission along the vertical axis via the Purcell effect. Additionally there is a degree of dislocation filtering that can occur [1]. However, one potential drawback of this device is the large free surface that borders the multi-quantum well active region. Nevertheless, it has been shown that the surface recombination in the nitride materials is the lowest of all III-V semiconductors. Results of SEM, PL, EL, and far field pattern are presented to compare the progressive effect of using photo-assisted electroless and wet etching [2]. It can be seen that over time the photo-assisted electroless method clearly delineates the active MQW region, possibly as a result of the different etch rate of InGaN. Alternatively, a purely chemical etching method was used. With a narrowing of the nanorods, there is a progressive blue shift of the photoluminescence peak. The optical image of the emission shows that there are well-defined lines of enhanced light propagation that match the symmetry of the nanorod array, thus showing there is a photonic crystal effect.