Tunneling Junction Diode Pressure Gauge

Abstract

Tunneling junction diodes were designed specifically for use as miniature pressure gauges. They were fabricated from arsenic doped germanium of resistivity 0.001 Ω-cm and tested under hydrostatic pressures up to 700 kg/cm2. Gauge factors of 350 were achieved and the change in ``peak'' current with pressure was shown to be comparable with that of Esaki diodes. These diodes differ from ordinary tunnel diodes in that the peak-to-valley ratio has been reduced to 1 or less by increasing the excess and diffusion currents via high temperature alloying and increased alloying times. A negative resistance region appears only at low temperatures. This type of flat-characteristic, two-terminal device is useful as a variable range pressure gauge by utilizing the pressure dependence of the tunneling current. These diodes have the advantage that they need not satisfy the strict stability requirements of the amplifier mode as does the tunnel diode when it is used in this manner; furthermore, bulky low inductance mounting is no longer needed. It is now possible to take full advantage of the extremely small size of these diodes, the working area of which may be as small as 0.076 mm in diam.