Optical waveguides formed by deuterium passivation of acceptors in Si doped p-type GaAs epilayers

Abstract

We report on the use of plasma hydrogenation of Si doped, p-type GaAs crystalline samples to form infrared waveguides through acceptor passivation. Epilayers grown by liquid phase epitaxy were exposed to a deuterium plasma for ninety minutes at three different temperatures. Secondary-ion mass spectrometry (SIMS) analysis indicated that the deuterium concentrations in the crystals after plasma exposure were nearly equal to the acceptor level and extended to depths between 2.0 and 4.0 μm. Reflectivity measurements showed that the epilayers had passivated regions whose thicknesses corresponded to those determined by SIMS analysis. Laser coupling experiments at 1.15 μm showed optical waveguiding in each sample and lowest propagation losses were on the order of 35 dB/cm. At a wavelength of 1.523 μm, only the sample processed at the highest temperature exhibited laser guiding and losses were considerably higher.