Nonmonotonic temperature dependence of the resistivity of p-Ge/Ge1−xSix in the region of the metal–insulator transition

Abstract

In a two-dimensional (2D) hole system (multilayer p-Ge/Ge1−xSix) heterostructure with conductivity σ≈e2/h at low temperatures (T≈1.5 K) a transition from the insulator phase (dσ/dT>0) to a “metallic” phase (dσ/dT<0) is observed as the temperature is lowered, behavior that is in qualitative agreement with the predictions of the Finkelstein theory. In a magnetic field B perpendicular to the plane of the 2D layer one observes positive magnetoresistance depending only on the ratio B/T. We attribute the positive magnetoresistance effect to the suppression of the triplet channel of Fermi-liquid electron–electron interaction by the magnetic field owing to the strong Zeeman splitting of the hole energy levels.

Acoustoelectric effects in very high-mobility p-SiGe/Ge/SiGe heterostructure at low temperatures in high magnetic fields

“…The value of the g-factor, therefore, depends on the Fermi energy. Indeed, at the bottom of the heavy hole band g=20.4, 15 while in the system with multiple quantum wells p-Ge/GeSi with density p≈1×10 11 cm −2 g = 14±1.4, 15 to be compared with our present result of g=4.5±0.3 for p=6×10 11 cm −2 . This is consistent with the findings of Ref.…”

Effective g factor of 2D holes in strained Ge quantum wells

“…However, until very recently, only a few values of the g ⊥factor in SiGe/Ge/SiGe structures have been present in literature. 1,[5][6][7] The first investigation of the g ⊥ -factor dependence on hole density was published in 2017. 8 Its authors studied the the g ⊥ -factor of 2D holes in a heterostructure field-effect transistor with low hole densities from 1.4×10 10 to 1.3×10 11 cm −2 .…”

Quantum Hall effect in p-Ge∕Ge1−xSix heterostructures with low hole mobility

“…We take notice that at B < 0.5 T positive magnetoresistance due to the effect of Zeeman splitting [19] is observed for all temperatures. At fields B > 0.5 T up to QHE r xx minimum a background negative magnetoresistance takes place with the following peculiarities observed: i) Shubnikov-de Haas (SdH) oscillation structure with maximum at B » 2 T, and ii) the r xx temperature-independent point at B B C » 1 (Fig.…”