Very smooth and vertical etching of InP by Cl2 reactive ion beam etching has been achieved under high temperature (≈200°C), high ion energy (≈1 keV) and low Cl2 pressure (∼10-5 Torr). The roughness is estimated to be a few nm by scanning tunneling microscopy and no contamination except for Cl was observed by in situ Auger electron spectroscopy. Under these etching conditions, the etched depth is precisely controlled (σ=22 nm) by simply monitoring the electrode curtent of the ion accelerating grid. Other III-V compound semiconductors, such as GaAs, InGaAs, AlGaInP and InAlAs have also been etched smoothly and vertically. Multilayers of these materials, such as InP/InGaAsP, AlGaInP/GaInP, and InAlAs/InGaAs/InP have been etched without steps between the layers on the sidewalls.

GaAs wires completely embedded in AlAs are successfully grown by molecular beam epitaxy at substrate temperatures higher than 725°C without interrupting growth. Crescent-shaped 1800-Å-wide GaAs wires are embedded in AlAs using this technique and electron beam lithography. We also investigate the dependence of photoluminescence on the GaAs wire width at room temperature. This investigation indicates that the emission efficiency of the narrowest GaAs wires (1800 Å wide) is at least as high as that of a quantum well grown on a planar substrate.