Sandy Barnes


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


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