Polarity-Selective Engineering of In-Gap States in Amorphous Silicon Nitride via Distinct Structural and Electronic...

Precise control of trap states in amorphous dielectrics requires identifying the fundamentally different physical origins of hole and electron trapping. Here, in amorphous silicon nitride (a‑SiN_x), we demonstrate a dual-origin mechanism where the two trap polarities arise from decoupled structural and electronic mechanisms, enabling polarity-selective engineering of charge storage behavior. Multi-spectroscopic characterization reveals that hole traps are dictated by structural disorder, where Si-rich nanoclusters form a percolating network whose cluster-size statistics exhibit power-law scaling characteristic of disordered connectivity. In contrast, electron traps are governed by electronic-level alignment, where Hf incorporation lowers the Fermi level, activates deep in-gap states, and introduces additional shallow levels near the conduction-band edge-without perturbing the optimized nanocluster states. By linking structural topology and electronic alignment to polarity-resolved trapping, this work establishes a unified physical picture of trap polarity in disordered dielectrics and provides a practical design route for next-generation charge-trap memories and amorphous nitride/oxide electronic systems.