ENGINEERING SERVICES ON TRANSISTORS.
Quarterly progress rept. no. 8, 1 Jan-31 Mar 65,
WESTERN ELECTRIC CO INC NEW YORK
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A low-resistance ohmic base contact for a planar germanium transistor is essential if maximum microwave performance of the device is to be achieved. A base contact employing a copper-germanium intermetallic layer, followed by titanium-aluminum or chromiumaluminum metallization has been shown to have satisfactory properties for the devices under current development. Devices using this contact have shown improved performance in the 1-to 6-Gc range. Results of a new simplified method of determining unilateral gain U from quantities that are relatively easily measured agree well with those obtained by other methods. Current limiters based on the high-field saturation of electrondrift velocity in germanium were fabricated by diffusing 10-micron-square n contacts, 2 microns apart, into a 0.5-micron-deep Sb-diffused layer having a surface concentration of about 10 to the 17th powercu cm. Limiting current was about 2.5 ma between 2 and 16 volts the conductance in the limiting range was approximately 0.00004 mho, and contact-to-contact capacitance was 0.1 pf. It has been shown that is is possible to design fast, nonsaturating logic circuits that are stable against spurious oscillation.