Appeal No. 96-3105
Application 08/135,003
The examiner's explanation of why there is a higher
concentration of P away from the source/channel junction is
missing. Lines 18-21, which the examiner relies on, discuss
that the source and drain contact windows are exposed to a
stream of phosphine and hydrogen, which indicates that the
chemical reaction will be uniform over the surface of the
window. This clearly implies that grading will be into the
substrate in a vertical direction and not lateral in a
horizontal direction as found by the examiner and shown in the
examiner's sketch. The optional heterojunction construction
in column 3 does not remove the Ga In As layer 12 over the
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InP substrate 11 as in the first embodiment of column 2,
line 60 to column 3, line 13. Wieder discloses that "[t]he
composition of the heterojunction may vary from that of InP
through the quaternary alloy In Ga As P up to the ternary
x 1-xy 1-y
alloy Ga In As" (col. 3, lines 26-29), which is what would
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be obtained in a vertical direction by exposing the Ga In As
0.47 0.53
layer 12 over the InP substrate 11 to a stream of phosphorus.
Wieder also discloses that "[t]he source and drain
heterojunctions optionally are made of other materials which
are lattice-matched to Ga In As yet have a larger bandgap"
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