Appeal No. 96-0341
Application 08/005,760
words, the examiner is of the opinion that Naito, like the
disclosed and claimed invention, has a forward current flowing
through the first diode (with the thinner base region under zone
32) that is greater than the forward current flowing through the
second diode (with the thicker base region under zone 31).
In Naito, the p-type layer 3 [anode zone] is composed of "a
first portion 31 which is thin in thickness and low in
concentration and second portions 32 which have a higher
concentration than the first portion 31 and are formed more
deeply than the first portion 31" (page 3, lines 33 through 36).
As a result of these impurity concentrations, when a positive
voltage is applied to the anode electrode 1 with respect to the
cathode electrode 2 to create a forward bias condition, "the main
current flows mainly through the first laminated structure I
wherein the first portion 31 serves as one of the emitters"
(emphasis added)(page 4, lines 7 through 9). Naito further
discloses that:
When the first laminated structure I thus becomes the
main current path, minority carriers contribute to
operation between the first portion 31 and the anode
electrode 1 because the diffusion potential is low and
the first portion 31 is thin. And the barrier between
the first portion 31 and the anode electrode is not an
obstacle to the carrier movement (emphasis added) (page
4, lines 9 through 12).
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Last modified: November 3, 2007