Postfabrication fine-tuning of photonic crystal microcavities in InAs∕InP quantum dot membranes

Abstract

A method to fine-tune photonic crystal defect cavities is developed based on successive oxidation and wet etching cycles. Photonic crystal microcavities based on InP membranes are oxidized using an ultraviolet (UV)/ozone treatment, and the oxide is subsequently removed using a hydrofluoric acid solution. Each oxidation/etch cycle consumes a thin layer of InP directly exposed to the UV/ozone, enlarging the radius of holes in the photonic crystal and decreasing the membrane thickness. The method is applied to single missing air-hole defect cavities with embedded InAs quantum dots, permitting measurement of the resonant frequency tuning in emission. Defect mode energies were found to blueshift 1.74meVpercycle, consistent with finite-difference time-domain simulations. A tuning range of 33meV was obtained after 20cycles.