Abstract
The magnetoresistance of GeхSi1-х (x = 0.002¸ 0.11) whiskers with an acceptor concentration (Na = 3x1018¸ 2.1019 cm-3) near the metal-insulator transition (MIT) was studied at low temperatures (4.2 - 77)K in magnetic fields up to 14 T. It is shown that at 4.2 K the magnetoresistance of the Ge-Si whiskers on thedielectric side of the MIT is quadratic, while the magnetoresistance of the crystals on the metal side of the MIThas an exponential dependence on the magnetic field. In the samples in the immediate vicinity to the MIT on thedielectric side, negative magnetoresistance was detected, whereas in metal samples with a high germaniumcontent (x = 11 at.%) an anomalous positive magnetoresistance occurs. The resulting anomalous dependences arerespectively explained by the conductivity with respect to the delocalized A+ states of the upper Hubbard bandand the increase in the electron-electron interaction in Ge-Si whiskers at increasing germanium content.
Highlights
Analysis of magnetoresistance character is one of the methods, which allows investigating conductance mechanism in solids, which determines their further application [1]
The composition of Ge-Si solid solution was controlled in the whiskers by microprobe analysis: germanium content was 1 ÷ 11 аt. %
Whisker magnetoresistance was measured at temperature 4.2 К in the range of magnetic field 0 ÷ 14 Т
Summary
Analysis of magnetoresistance character is one of the methods, which allows investigating conductance mechanism in solids, which determines their further application [1]. Carrier transport in Ge-Si solid solutions, in particular in quantum dot arrays was studied in the work [2]. Magnetic-field dependences of the conductivity associated with hopping transport of holes over a 2D array of Ge/Si(001) quantum dots [3]. There are many works [4,5,6] devoted to theoretical and experimental studies of whisker magnetoresistance in Si and Ge. The authors of [7] investigated magnetoresistance in Si whiskers at temperature 4.2 K. Mechanism of carrier transport is not enough investigated at the range of cryogenic temperatures in Ge-Si whiskers with greater Ge content
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