Abstract

Reactive-ion etching to form rib waveguides in semiconductors is preferable to wet etching because of increased uniformity, better depth control, reduced mask under-cutting, and reduced side-wall slope. In this summary we report the fabrication of single mode rib waveguides in GaAs/AlGaAs quantum well systems by using CCl₂F₂/O₂. The self-aligned oxidized Ti etch mask defines the electrodes and the ribs in a one step process. CCl₂F₂ was selected as the etchant because of its combination of high etch rate in GaAs and nontoxicity. The oxidized Ti mask used has provided the necessary etch resistance needed for deep etching, the result of the continuous oxidation of the Ti by the oxygen rich plasma. It is also easily removed for electrode contacts and adheres well to the gold electrode. The sample was an MBE grown waveguide on a Si doped {100} substrate. Ohmic contacts of gold/chromium/gold (10 nm/25 nm/200 nm) were e-beam deposited followed by 350 nm of Ti. Waveguides were patterned on the Ti by using photoresist and a chemical etch of 100:1 HF. Optical properties of the waveguide will be presented and compared with those of chemically etched waveguides.

© 1992 Optical Society of America