Криогенные термометры сопротивления на основе пленок Ge–InP. Технология и конструирование в электронной аппаратуре

Abstract

Despite the large number of scientific articles devoted to the development of cryogenic resistance thermometers, not many of these thermometers are mass-produced. As is know, semiconductor resistive temperature sensors have low magnetoresistance and high resistance to radiation. The purpose of this work was to manufacture thin (170—190 nm) Ge films on semi-insulating InP substrates, which can be used to create cryogenic resistance thermometers with high temperature sensitivity and relatively low sensitivity to magnetic field that can operate in the 1.5—400 К temperature range. Films of Ge on InP (100) can be used to produce cryogenic resistance thermometers. They have good thermal sensitivity and relatively low magnetoresistance. The films were produced by thermal evaporation of Ge in vacuum (2•10-4 Pa) on semi-insulating InP (100) substrates. The temperature of the InP substrate during film deposition was 310°C, the deposition rate was also constant during sputtering, but varied in the range of 0.03 to 0.06 nm/s for different films. Ge films were p-type conductivity with a resistivity of 0.2—0.3 Ω•cm, hole concentration (3—5)•1018 cm–3 and Hall mobility 6.5—7.5 сm2/(V•s) at room temperature. The quality of the Ge–InP heterostructure was determined by high-resolution X-ray diffraction on a Philips MRD diffractometer. The nanomorphology of the surface of Ge films was studied using the NanoScope IIIa atomic force microscope. The crystal structure of the films is amorphous or polycrystalline with a low level of structural perfection. The effective value of the surface roughness is from 2.25 to 2.60 nm. The obtained resistance values at different temperature in the range of 2—25 K were described by exponential dependence. Corrections in temperature measurement are 5% in a magnetic field of 11 T at a temperature of 4.2 K and 14% in a magnetic field of 14 T at a temperature of 2.2 K. The research results indicate that the obtained films can be used to measure cryogenic temperatures in magnetic fields of up to 14 T.