Appeal No. 1998-2938
Application 08/510,752
lattice constant (strain) and does not disclose or suggest a
quantum well layer having a non-uniform lattice constant or
strain profile across the thickness.
As we understand the Examiner's position, Zucker
discloses materials that can be used to produce polarization
independence by a quantum well layer that is lattice
mismatched (strained) to the rest of the structure (the
substrate or a barrier layer), Zucker teaches that equivalent
structures can be implemented in other material systems
including the materials in Ishikawa, and that substitution of
strain inducing materials for the stacked layers of materials
with constant lattice value in Ishikawa will inherently result
in a quantum well layer with a non-uniform lattice constant.
We disagree with this reasoning. Ishikawa and Zucker produce
polarization independence in very different ways: Ishikawa by
a non-uniform composition with constant lattice constant, and
Zucker by a uniform composition having strain. There is no
suggestion in Ishikawa of using stacked layers with mismatched
lattice constants and there is no suggestion in Zucker to have
more than one strained layer; i.e., neither Ishikawa nor
Zucker discloses a quantum well layer with a non-uniform
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