Structure and galvanomagnetic properties of two-phase recrystallised InSb-In layers

Abstract

Two-phase alloys of InSb-In have been prepared by the controlled melting and recrystallisation of polycrystalline InSb layers overcoated with thin, metallic In films. X-ray diffraction shows that recrystallisation brings about a preferential crystallographic ordering of {111} in the plane of the film. Electron micrographs, etching and metallographic studies reveal webbed InSb dendrites several mm long separated from each other by discontinuous In filaments embedded in an InSb matrix. The magnetoresistance (Δ ρ/ρ0) t of such a two-phase film is dominated by the microgeometry of the dendrites, their density, and distribution. It is independent of macroscopic geometrical factors; the Hall coefficient 〈 R h 〉 has the expected theoretical dependence on specimen shape and electrode configurations. An essentially qualitative interpretation of the measured temperature dependence of (Δ ρ/ρ0) t and 〈 R h 〉 suggests a superposition of two charge carrier transport mechanisms: the geometrical (Δ ρ/ρ0) of the near-intrinsic dendrites is shunted by the physical magnetoresistance of the acceptor-doped matrix. At 295°K, typical two-phase recrystallised films 1·5 to 2· μ thick have a (Δ ρ/ρ0) t ⋍ 4 at H = 2 × 10 4 G and a virtual electron mobility (calculated from Hall measurements) in the range 2·2 × 10 4 ⩽ μ n ⩽ 3·2 × 10 4 cm 2/(V-sec.).