Appeal No. 1997-1249
Application 08/179,601
n-doped, intrinsic, p-doped and intrinsic layers in
such a superlattice.
The recombination of electrons from the n-type
layers with holes from the p-type layers results in
a periodic charge variation in the superlattice that
produces a periodic variation in the bottom of the
conduction band and in the top of the valence band,
thereby producing a periodic array of potential
wells as in a compositional superlattice. This also
results in a separation between the holes and the
electrons so that the recombination time for excess
holes and electrons is greatly increased. When
excited optically or electrically, a large number of
excess holes and electrons are created that flatten
the periodic potential and increase the effective
band gap (defined as the distance between a minimum
in the bottom of the conduction band and a maximum
in the top of the valence band) of the superlattice.
Therefore, the electrical and optical properties can
be varied by varying the number of excess holes and
electrons in the superlattice. (Emphasis added.)
Thus, the i layer of Doehler is not required, and does
not contribute to its optical properties. Therefore,
increasing the thickness of the i layer would not increase
sensitivity in Doehler, even if it would have increased
sensitivity in Yamazaki.
The Federal Circuit states that "[t]he mere fact that the
prior art may be modified in the manner suggested by the
Examiner does not make the modification obvious unless the
prior art suggested the desirability of the modification." In
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