Piezoresistance in defect-engineered silicon

Archive ouverte : Article de revue

Li, Heng | Thayil, Abel | Lew, Chris | Filoche, Marcel | Johnson, Brett | Mccallum, Jeff | Arscott, S. | Rowe, Alistair,

Edité par HAL CCSD ; American Physical Society

International audience. The steady-state, space-charge-limited piezoresistance (PZR) of defect-engineered, silicon-on-insulator device layers containing silicon divacancy defects changes sign as a function of applied bias. Above a punch-through voltage (Vt) corresponding to the onset of a space-charge-limited hole current, the longitudinal ⟨110⟩ PZR π coefficient is π≈65×10−11 Pa−1, similar to the value obtained in charge-neutral, p-type silicon. Below Vt, the mechanical stress dependence of the Shockley-Read-Hall (SRH) recombination parameters, specifically the divacancy trap energy ET that is estimated to vary by approximately 30μV/MPa, yields π≈−25×10−11 Pa−1. The combination of space-charge-limited transport and defect engineering that significantly reduces SRH recombination lifetimes makes this work directly relevant to discussions of giant or anomalous PZR at small strains in nanosilicon whose characteristic dimension is larger than a few nanometers. In this limit the reduced electrostatic dimensionality lowers Vt and amplifies space-charge-limited currents and efficient SRH recombination occurs via surface defects. The results reinforce the growing evidence that in steady state, electromechanically active defects can result in anomalous, but not giant, PZR.

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