Fabrication of Nanopillars comprised of InGaN/GaN Multiple Quantum Wells by Focused Ion Beam Milling

Focused ion beam (FIB) direct milling of InGaN/GaN MQWs samples are performed with a beam-shape tuning process deliberately, and site-controlled high-aspect-ratio nano-pillars were anomalously produced, without any lithographies. The swelling of p-GaN tip induced by the ion beam live-irradiation served as low-milling-rate sites - the sites on which the resultant nanopillars form. The bump (or blister) formation mechanism is complicated but indeed plays an important role in heightening the nano-pillar. The retained quantum well (QW) discs inside the pillar emitted a sharp and discrete peak at 415 nm, showing a blue shift of 35 meV with respect to the bulk sample. The peak intensity was even enormously enhanced after subsequent wet-etching. Our results imply an alternative method for maskless and site-controlled nano-rod writing, and pave out a way for FIB prototyping III-nitride optical devices.