|
|
Oral History – Sandy Barnes (Continued)
|
|
Before we discuss the
silicon diode program, what other early work on transistors do you
remember?
In July 1949, Bell Labs
published a compendium of transistor technology papers, which were to
become the “bible” for the early investigators of this new and interesting
device. This Bell System Technical
Journal proved to be an important link between the staff and the outside
physics community. For the next few
years, my copy of this publication became worn and dog-eared from use, as
this was the only source of transistor theory at that time. This early work at Hughes was started by
Dr. North and myself, on a six foot bench in a corner of the missile lab in
Culver City, Ca. Si Ramo and Dean
Wooldridge saw the potential of semiconductors for military electronic
systems, and this early 1949 work kept Hughes at the leading edge of
semiconductor technology for many years.
Grown junction transistors appeared in 1951. These consisted of a tiny rod-shaped
piece of Ge, treated so that it contained a thin electrically positive
layer sandwiched two electrically negative ends. The technology of growing
single crystals of Ge, Si and other semiconductors was developing over the
years, with objectives aimed at crystal perfection and purity, increasing
the mobility of electrons and holes,
and size of ingots. As this
technology advanced, fabrication of p-n junction devices was made possible
by doping the melt with “n” and “p” type impurities.
|
|
|
Oral History – Sandy Barnes (Continued)
|
|
At Hughes, during 1951, I
built one of the first crystal growing furnaces west of BTL, for producing
single crystals. Later, I started doping the melt for making p-n junction
devices. A p-type ingot was grown
for a short length, then doped with an n-type impurity, grown briefly as an
n-type, then doped with p-type impurity.
By this time the Hughes R&D department was staffed with 6 or 8
people from BTL and universities, and significant progress was made with
silicon material and diffusion techniques.
I filed a patent in 1952
related to n-p-n junction transistors, which were of great interest to
Hughes Aircraft for their application in high frequency radar and
communications equipment for the military.
At that time, only p-n-p transistors were being made
successfully. The n-p-n devices
were electrically superior because of greater mobility of electrons as
compared to holes being the current carrier in p-n-p transistors. The invention here was to use a fused
contact of antimony, tin and bismuth to produce the n-type regions. The limitations of grown junction
transistors finally put a hold on any further development of these devices
and Hughes’ attention was focused on the development of a glass enclosed
package for diodes.
Go
To Barnes Oral History, Page 4
|
|