Fabrication of 2D photonic crystal nanocavity membrane

This paper addresses the fabrication technique of two-dimensional (2D) photonic crystal (PhC) membrane with nanocavity structures. Hexagonal lattice of air holes with periodical variation of refractive index embedded in high-index semiconductor results in strong dispersion of light. Electron beam lithography (EBL) technique was employed to transfer high resolution pattern onto a sample coated with electronic resist. The e-beam is deflected to direct write the chosen pattern. The sample consists of three-layer semiconductor with the top layer being the 320nm-thick GaAs with MBE grown InAs quantum dots (QD) at the center of the layer, followed by the sacrificial 1.5 mu m-thick Al0.7Ga0.3As layer and GaAs layer as the substrate. A 234nm-diameter cavity 2D PhC suspended membrane was fabricated with about 12 mu m diameter of the chamber below it.