Sensitive element of multifunctional sensor for measuring temperature, strain and magnetic field induction has been developed based on the studies of electrical conductivity and magnetoresistance of silicon and germanium microcrystals in the temperature range 4.2—70 K, strain ±1.5×10–3 rel.un. and magnetic fields of 0—14 T. The feature of the sensitive element is the using of the p- and n-type conductivity germanium microcrystals as mechanical and magnetic field sensors, respectively, and the p-type silicon microcrystal — as temperature sensor. That allows providing the compensation of temperature influence on piezoresistance and on sensitivity to the magnetic field.
Studies of low-temperature features of semiconductor silicon whisker conductivity play a significant role in the development of electronic devices, such as temperature sensors. The results of studies of the active component of impedance Z' for silicon whiskers obtained at cryogenic temperatures, indicating the increase of its value under temperature decreasing, and showing the frequency dependence in the range from 0 to 250 kHz. It was found that in temperature range 4.2–20 K at a frequency wêð which can amount from 8 to 20 kHz, depending on resistivity and temperature, the hopping conduction with the participation of phonons is observed in whisker samples, resulting in a significant reduction of Z' value at frequencies up to 250 kHz. For example, at a temperature of 4.2 K for the sample with resistivity r300K=0.0168 Ohm×cm the frequency wêð is equal to 8 kHz, and in frequency range up to 250 kHz the active component of impedance is reduced approximately by half. Such behavior of the frequency response for these samples is kept up to 20 K, whereas at 25 K the value of Z' is almost independent of frequency, and at higher temperatures with the increasing of frequency, it slightly increases. Reducing the resistivity of the samples leads to a narrowing of the temperature range, where the hopping conduction is observed, and at r300K = 0.0143 Ohm×cm it is observed only at a helium temperature. Offset of the frequency wêð from 8 to 20 kHz at the hopping conduction beginning, depending on temperature and the value of resistivity for studied silicon crystals, can be attributed to the change of free charge carriers concentration in such samples, because it determines the effect of Coulomb gap on wêð. Experimental study of low-temperature conductivity of silicon whiskers allowed proposing the temperature sensor operable at temperature range 4.2–100 K. The sensor works on alternating current, because it avoids the sell-heating of sensitive element and the occurrence of «parasitic» thermopower, which also affects the accuracy of temperature measurement.
Temperature dependencies of Bi2Se3 whiskers’ resistance with Pd doping concentration of 1´1019 cm-3 where measured in temperature range 4.2 - 300 K. At temperature 5.3 K a sharp drop in the whisker resistance was found. The observed effect is likely connected with contribution of two processes such as the electron localization in the whiskers and transition in superconducting state at temperature 5.3 K, which is likely result from Pd complexes.Transversemagnetoresistance in n-type Bi2Se3 whiskers with Pd doping concentration in the vicinity to themetal-insulator transition (MIT) from metal side of the transition were studied in magnetic field 0 -10 T. For the whiskers a resistance minimum was observed at temperature about 25 K that is connected with Kondo effect.
Äîñë³äaeåíî âëàñòèâîñò³ øàð³â ïîë³êðåìí³þ íà ³çîëÿòîð³, íåðåêðèñòàë³çîâàíèõ òà ï³ñëÿ ëàçåðíî¿ ðåêðèñòàë³çàö³¿, ëåãîâàíèõ áîðîì, â òåìïåðàòóðíîìó ä³àïàçîí³ 4,2-300Ê ³ â ñèëü-íèõ ìàãí³òíèõ ïîëÿõ äî 14Ò. Ïðîâîäèëèñü âèì³ðþâàííÿ òåìïåðàòóðíî¿ çàëåaeíîñò³ îïîðó íåðåêðèñòàë³çîâàíèõ ³ ðåêðèñòàë³çîâàíèõ øàð³â ïîë³êðåìí³þ ç ð³çíîþ êîíöåíòðàö³ºþ íî-ñ³¿â â³ä 3·10 ñì -3 â ³íòåðâàë³ òåìïåðàòóð 4,2-300Ê, à òàêîae ìàãí³òîîïîðó âñ³õ äî-ñë³äaeóâàíèõ çðàçê³â ïðè ãå볺âèõ òåìïåðàòóðàõ. Âèçíà÷åíî êîíöåíòðàö³¿ íîñ³¿â çàðÿäó øà-ð³â ïîë³êðåìí³þ íà ³çîëÿòîð³, ïðèäàòíèõ äëÿ ñòâîðåííÿ ñåíñîð³â òåìïåðàòóðè ³ ïºçîðåçèñ-òèâíèõ ñåíñîð³â ìåõàí³÷íèõ âåëè÷èí, ïðàöåçäàòíèõ ïðè êð³îãåííèõ òåìïåðàòóðàõ ³ â ñèëü-íèõ ìàãí³òíèõ ïîëÿõ.Êëþ÷îâ³ ñëîâà: øàðè ïîë³êðåìí³þ íà ³çîëÿòîð³, ëàçåðíà ðåêðèñòàë³çàö³ÿ, êð³îãåíí³ òåì-ïåðàòóðè, ïºçîîï³ð, ìàãí³òîîï³ð, ñåíñîðè òåìïåðàòóðè ³ ìåõàí³÷íèõ âåëè÷èí. The properties of boron doped polysilicon-on-insulator layers, unrecrystallized and after laser recrystallization, in the temperature range 4.2-300K and in high magnetic fields up to 14T were studied. Temperature dependencies of resistance for unrecrystallized and recrystallized polysilicon layers with different carrier concentration from 3·10 ñì -3 as well as the magnetoresistance of all studied layers at liquid helium temperatures were measured. There were determined carrier concentrations of polysilicon-on-insulator layers sutiable to create on their basis the temperature sensors and piezoresistive mechanical sensors, operating at cryogenic temperatures and in high magnetic fields. Summary STUDY OF POLYSILICON-ON-INSULATOR LAYERS LOW-TEMPERATURE CHARACTERISTICS TO CREATE TEMPERATURE AND MECHANICAL SENSORS
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