Sensors of magnetic-field (sensors of Hall) on the basis of tapes of GaAs
Technical descriptions of sensors of magnetic-field on the basis of effect of Hall (sensors of Hall) depend both on the used material and from geometrical sizes and form of pickoff [1,2]. Most often for the pickoffs of sensors of Hall use such materials as InSb and GaAs, basic advantages of which consist in high mobility of transmitters of charges, resulting in the high sensitiveness of sensors.
In a lecture the results of development and experimental research of metrology descriptions of transducers (sensors) of magnetic-field and influence of neutron irradiation are presented on basic parameters.
For creation of sensors tapes of GaAs are used on a semiinsulating gaas. The purpose of development was creation of sensors with the low levels of noises, high linearness of dependence of useful signal from magnetic-field, by weak dependence of parameters on a temperature, and similarly miniature of working area. On a fig. 1 the chart of pickoff of sensor is shown.
Fig. 1.Schematic image of pickoff of sensor of Hall
The thickness of tapes of СаАs was varied within the limits of 0.1-5 μm, concentration of transmitters of current of ≅ 5·10^18 sm^- 3. Size of working area of 100 х 100 μm. Depending on the thickness of tapes and concentration of transmitters of current entrance and output electric resistances of sensors changed within the limits of 15 - 1500 Ohm. Currents of feed of 3 - 150 mA. An initial output signal of Uo was within the limits of 0.01 - 5 mV, temperature dependence of Uo less than 0,1%/K, R ~ 0,08 %/K, sensitiveness to the magnetic field within the limits of 80 - 500 mV/T. Linearness of output signal in the field to 2 T not worse 0,1%. Sensors can work in the range of temperatures 4.2 - 400 К.
It is known, for example [2-4], that firmness of semiconductor devices to the radiation irradiation depends on the level of alloying, imperfectness of semiconductor material of and other. On electrophysics properties of semiconductors most influence renders a neutron irradiation. Thus the mechanism of influence consists mainly in formation of structural defects and radio-active transformation of atoms. With the increase of level of alloying of влия ние irradiation relaxes.
Descriptions were measured by us at a temperature 300 K the irradiation and after an irradiation the streams of Ф of neutrons from 8х10^14 sm- 2 to 1х10^17 sm- 2. A temperature at measuring was stabilized within 0.1 К. Energy of neutrons 1 MeV, intensity of stream (2-4) of х10^8 fl/s.
Fig. 2. Dependence of relative change of entrance resistance of Rn / R (1) and initial output signal of Un/U (2) measuring transducer of magnetic-field from the size of irradiation the streams of neutrons.
On a fig. 2 dependence over of relative change of entrance resistance of measuring transducers of magnetic-field (sensors of Hall) is brought on the size of stream of neutrons. Entrance resistance of sensors of 1.1 kOhm, initial output signal no more than 4.5 mV, sensitiveness of 350 mV/T. The changes of resistance begin at the streams of 1х10^15 sm- 2 and make a size 15-20 %, and at 1х10^16 sm- 2 resistance increases in 3.3 time. Thus initial output signal at permanent tension of feed 4.5 In changed no more than on 15 %, that equivalently to influence of magnetic-field a size to 1 mT. At permanent tension of feed a sensitiveness after an irradiation diminished approximately in 1.4 time. After an irradiation the streams of 1х10^17 sm- 2 resistance of sensors grows for ever and ever.
Thus, the sensors of magnetic-field are capable of working in the wide range of temperatures, possess weak temperature dependence of sensitiveness and initial output signal (less than 0.1%). Non-linearity of output signal does not exceed 0.1% in the field to 2 T, a sensitiveness can arrive at 500 mV/T.
The researches conducted by us showed that at 300 К the worked out sensors are capable of working to the levels of neutron irradiation a 10^15 sm - 2. The nascent changes of descriptions of transducers to the levels of 1х10^16 sm- 2 can be up to a point taken into account, due to that good repetition of results was. Transducers can be used both for diagnostics of technical devices of atomic energy, cryogenic technique and, due to a high sensitiveness, in ecology for control of parameters of environment, such as the electromagnetic fields of and other
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