Fabrication of Submicron Gratings for 1.5 μm InGaAsP / InP Distributed Feedback Lasers by Reactive Ion Etching Using C 2 H 6 / H 2

Abstract

Etching conditions for submicron period gratings on substrates by reactive ion etching using a mixture have been systematically investigated. Etching rates and shapes of grooves in samples are assessed after being etched under various gas pressure conditions, flow ratios, and RF power densities. The pressure affects the angle of the etched side wall. The selective deposition of organic compound in the etching process can be controlled by the flow ratio. It was proven that the depth of the grooves are controllable up to 700 nm by adjusting the etching conditions. The technique has been applied to form gratings with a period of 240 nm for distributed feedback (DFB) lasers. The lasers have threshold currents ranging from 30 to 45 mA, which are comparable to those of DFB lasers fabricated by conventional wet chemical etching. Gratings with a period of 135 nm were also fabricated on an substrate by reactive ion etching, using a technique which halves periods of gratings.