The Ge thermometers are made from heavy doped and compensated bulk Ge. Doping is carried out using a set of impurities with various activation energies by both the metallurgical method and neutron transmutation method. These thermometers cover the temperature range for operation from 0.3 to 300 K.

Temperature dependencies of resistance and sensitivity S=dR/dT for the different types of the Ge-bulk thermometers

Effect of magnetic field on thermometers 

Depending on the magnetic field value and temperature, the magneto-resistance for different types of thermometers can be positive or negative.  The presence of magneto-resistance effect results in an error of temperature determination.  Such an error can be presented as the ratio DT/T (%), where DT = T(B) - T,  T is a temperature measured at B = 0, and T(B) is some temperature measured in the magnetic field B.

Typical temperature errors, DT/T (%), as function of magnetic field , B (Tesla), and temperature, T (K),  for Ge-bulk thermometers of  G-4/273 model