Investigating the Strain Effect in Nickel- and Tin-Doped Silicon Schottky Barrier Diodes Under Hydrostatic Pressure

Abstract

This work investigates the strain-sensitivity of Schottky barrier structures fabricated on silicon pre-doped with isovalent impurities and subsequently compensated with deep-level nickel impurities. The study demonstrates that while isovalent impurities themselves typically do not alter electrophysical parameters, the presence of deep-level nickel impurities significantly enhances the semiconductor's sensitivity to mechanical stress. The research was conducted under all-round hydrostatic pressure (AHP) to evaluate the piezoresistive properties of these structures. A key challenge addressed is the creation of Schottky barrier diodes (SBDs) that combine high strain-sensitivity - requiring high-resistivity compensated material - with a significant contact potential difference, which necessitates low-resistivity material for effective barrier formation. We show that predoping silicon with isovalent tin impurities inhibits uniform nickel diffusion, resulting in Si<P,Sn,Ni> structures with a non-uniform resistivity profile. This engineered structure features a highly compensated region for enhanced strain sensitivity and a near-surface low-resistivity zone for forming an effective Au-Sb Schottky barrier. Current-voltage characterization under AHP reveals that the relative change in forward current (ΔI/I₀) in Si<P,Sn,Ni>-based SBDs shows a strong voltage dependence with a characteristic peak, attributed to pressure-induced voltage redistribution between the potential barrier and compensated base region. Significantly, enhanced strain-sensitivity is achieved even in high-resistivity (10⁴-10⁵ Ω·cm) Si<P,Sn,Ni> structures, a result unattainable in uniformly compensated Si<P,Ni> samples. These findings establish that controlled non-uniform impurity distribution through isovalent pre-doping is crucial for developing highly sensitive piezoresistive semiconductor devices.