Non-lithographic nanopatterning of InGaN/GaN multiple quantum well nanopillars by focused ion beams

摘要

This study proposes a new approach to fabrication of a high-aspect-ratio InGaN/GaN multiple quantum well nanopillar array. This fabrication technique utilizes focused ion beam milling with modified beam-shape tuning technology. The samples used in this work have a light-emitting diode (LED) structure grown by metal-organic chemical-vapour deposition. The modified beam-shape tuning was performed by simultaneously stigmating and defocusing the ion beam. The structural and optical properties of the ion-beam-milled areas were examined by high resolution transmission electron microscopy and thodoluminescence (CL). Typical nanopillars have diameters of about 100-150 nm and heights of about 600-1000 nm. The corresponding CL spectrum at room temperature revealed the main emission to be approximately 2.98 eV, and it showed a blue shift of about 35 meV compared to as-grown samples. A maskless, site-controlled approach to the fabrication of nano-LEDs was demonstrated in this work.