Space-Charge-Driven Nonlinear Charge Transport in Silicon Reconfigurable Nonlinear-Processing Units

Abstract

Reconfigurable nonlinear-processing units (RNPUs) are multi-terminal electronic devices that act as computational primitives, exploiting intrinsic nonlinear charge transport combined with electrostatic tunability. Silicon-based realizations provide a scalable and technologically relevant platform toward unconventional computing hardware, yet the physical origin of their room-temperature nonlinearity has remained unresolved. Here, we demonstrate room-temperature operation in both boron- and arsenic-doped silicon RNPUs and show, using temperature- and length-dependent measurements supported by TCAD simulations, that charge transport is governed by space-charge effects. Interface trap states strongly suppress the equilibrium carrier density, while the functional nonlinearity arises from the competition between injected carriers and ionized dopants. The resulting transport evolves from Ohmic to strongly nonlinear and space-charge-limited current regimes, as evidenced by voltage and length scaling. The opposite-polarity background doping is shown to control the onset and strength of the nonlinearity, producing behavior beyond the quadratic dependence of the classical Mott-Gurney law. Agreement between experiment and simulation supports that the spatial distribution of injected carriers and fixed charge governs the electric-field profile and device response. These results establish a space-charge-based framework for RNPUs that does not require disorder or hopping transport, and provide design guidelines for scalable, CMOS-compatible nonlinear computing hardware.