Cryogenic Diode Thermometer Insensitive Completely to Magnetic Fields Up to 1 T

The article presents investigation results concerning silicon p-n junction diodes with heightened diode base doping level up to a critical value for the insulator-metal transition. Accent is made on application of such the diodes as temperature sensors in cryogenic region and in the presence of magnetic fields, i.e. under conditions when available commercial silicon diode temperature sensors become inapplicable. The reason is a freezing-out of the free current carriers in their lightly doped bases. In this case the base conduction becomes hopping with large magnetoresistance, and an impact ionization of the frozen-out carriers in the electric field results in electrical instability (hysteretic phenomena in the current-voltage characteristics). It is shown that the diodes investigated are free of the electrical instabilities inherent in the commercial diodes, and can operate with much lower the sensor working currents. The lower the operating current, the smaller is the measurement error connected with magnetic-field influence. At the operating currents of 10 and 1 μA, the sensor proves to be insensitive completely to magnetic fields up to 1 T.