Bernard N. Slade

Oral History Bob Slade (Continued)



Photograph 2005 by Bob McGarrah.

Used with permission.


Magnified view of a 1950 era TA165 Point Contact Transistor


Above is a section of a patent awarded to Bob Slade, which documents important aspects of his pioneering work with point contact transistors. The April 21, 1950 filing date represents a very early timeframe in semiconductor technology, and is less than two years after the public announcement by Bell Labs of the invention of the transistor. One of the device parameters relevant to point contact transistor operation is the spacing between the two points (emitter and collector) shown as items 13 and 14 in the patent figures above. Varying the spacing in a range between 1 mil to 5 mils results in devices with varying performance in terms of gain, stability and frequency capability. The above patent provides a methodology for understanding this phenomenon. The photo to the left is a close-up view of a 1950 era point contact transistor developed by Bob. The similarity of the device to the patent figures is striking. Note the key feature of point contact technology two sharpened point contacts physically pressed against a germanium block. These first transistors were difficult to manufacture, physically fragile and subject to unpredictable performance nonetheless, the work done to characterize these early devices helped to establish the basis for the resultant dramatic improvements in semiconductor technology over the next decade.


Go To Slade Oral History, Page 6


COPYRIGHT 2001, 2005 by Jack Ward. All Rights Reserved. http://www.transistormuseum.com/