Selective lateral electrochemical etching of a GaN-based superlattice layer for thin film device application.

We propose and demonstrate a selective lateral electrochemical etching using a superlattice as the etch-sacrificial layer. Differing from the previous methods that require a special etch-sacrificial layer and therefore deteriorate the epilayer grown atop, our method simplifies the epi-growth without compromising the epi-quality. At the reverse bias voltage of 20 V in 0.3 M oxalic acid electrolyte, a 50-nm-thick InGaN/AlGaN superlattice was etched laterally at the rate of ∼0.8 μm/min. Our method is efficient enough for the epitaxial lift-off process: an array of 80 μm × 80 μm square platelets is completely detached from substrate, with quantum-well emission properties preserved intact. [ABSTRACT FROM AUTHOR]