PROJECT TITLE :

Investigation of electrochemical etch differences in AlGaAs heterostructures using Cl2 ion beam assisted etching

ABSTRACT:

A deeply etched, anisotropic 45° and 90° mirror technology is developed for AlxGa1−xAs heterostructures using a Cl2 ion beam assisted etching system. When etching vertically, using a conductive low-erosion Ni mask, electrochemical etch differences between layers with various Al mole fractions caused nonuniform sidewall profiles not seen in semi-insulating GaAs test samples. These variations, based on alloy composition, were found to be negligible when etching at a 45°. A Si3N4-Ni etch mask is designed in order to electrically isolate charge buildup caused by the incoming Ar+ ion beam to the Ni layer, preventing conduction to the underlying epitaxial layers. This modification produced smoothly etched facets, up to 8 μm in depth, enabling fabrication of substrate–surface-emitting slab-coupled optical waveguide lasers and other optoelectronic devices.