A method and apparatus for forming tapered thickness and material content of III-V material, or alloys thereof, in particular GaAs and AlGaAs, by gradient thermal heating of substrates during epitaxial growth and the optoelectronic structures formed thereby....http://www.google.com.au/patents/US4855255?utm_source=gb-gplus-sharePatent US4855255 - Tapered laser or waveguide optoelectronic method
