MECHANISMS OF PIEZORESISTIVITY IN COMPENSATED SILICON WITH DEEP-LEVEL IMPURITIES UNDER HYDROSTATIC PRESSURE

Abstract

This study investigates the mechanisms of the piezoresistive effect (tensoeffect) in compensated silicon doped with deep-level impurities (Mn, Ni, Gd) under the influence of all-round hydrostatic compression. The research addresses the problem of interpreting changes in electrical conductivity, which are often ambiguous under isotropic deformation due to the simultaneous variation of carrier concentration and mobility. The applied methodology involves the development of a theoretical model based on the analysis of provided experimental data for n- and p-type Si<Ni> and Si<Mn>. The model accounts for pressure-induced shifts of deep impurity levels and the conduction/valence band edges, which alter the ionization degree of scattering centers and the free carrier concentration. Key results include the quantitative determination of the baric coefficient for the ionization energy of the Mn level (α ≈ 1.81·10⁻¹¹ eV/Pa) and for Ni/Gd levels (α ≈ -0.7·10⁻¹¹ and -0.8·10⁻¹¹ eV/Pa, respectively). It is shown that in Si<Mn>, the piezoresistive effect is primarily governed by changes in carrier concentration, while in Si<Ni>, the redistribution of carriers between deep levels and bands, along with the influence of potential barriers from Ni precipitates, plays a decisive role. The main conclusion is that the piezoresistive response in heavily compensated silicon under hydrostatic pressure is dominantly controlled by the electronic properties of deep-level impurities and related structural inhomogeneities, rather than by intervalley scattering mechanisms [1]. This provides a foundation for the development of sensitive pressure sensors based on compensated semiconductor structures.