Influence of thickness on the galvanomagnetic properties of thin InSb films for highly sensitive magnetoresistance elements

Abstract

Thin InSb films were prepared on mica substrates by evaporation of InSb to obtain highly sensitive magnetoresistance (MR) elements with high element resistance. The MR effect was investigated for elements with a thickness range of 0.15–0.5 μm. It was observed that only the 0.15-μm-thick InSb film consists of a p-type, [111]-oriented single crystal, while the films thicker than 0.2 μm show n-type conduction. At room temperature, in a magnetic field of 1 T, the n-type films with thicknesses of 0.2, 0.3, and 0.5 μm and length-to-width ratios of 0.12, 0.09, and 0.05, were found to have increasing mobilities of 2.2, 4.4, and 5.0 m2/V s, decreasing element resistances of 115, 44, and 16 Ω, and increasing MR(ΔR/R0) values of 394, 652, and 800%. Measurements of the temperature dependence of μ show that 0.15–0.3-μm-thick films have a small temperature coefficient of MR values at room temperature because μ peaks near that temperature. The 0.15–0.3-μm-thick InSb films are therefore most useful for low-cost MR elements because of their high element resistance, small temperature coefficient of electron mobility, and high sensitivity.