2025/05/01 by Mingyu Xie, Ruitian Chen, Xie, Mingyu +13
Physics and Astronomy · #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.2505.00575
The total rate of carrier recombination in semiconductors has conventionally been expressed using an additive model, rtotal = Σri , which rules out the interactions between carrier recombination pathways. Here we challenge this paradigm by demonstrating pathway competitions using our newly developed light-induced mechanical absorption spectroscopy (LIMAS), which allows us to probe genuine recombination dynamics in semiconductors via mechanical damping. We show that the total recombination rate in zinc sulfide (ZnS), a model semiconductor material, follows a multiplicative weighting model, rtotal ∝ Πri ^(wi) with Σwi=1. Under both steady-state and switch-on illuminations, the weighting factors wi for each recombination pathway-direct, trap-assisted, and sublinear-are dictated by the carrier generation mechanism: (i) interband transition favors direct recombination; (ii) single-defect level-mediated generation promotes trap-assisted recombination; (iii) generation involving multiple saturated defect levels gives rise to sublinear recombination. Upon light switch-off, localized state changes drive a dynamic evolution of wi, altering pathway competitions. These findings reshape our fundamental understanding of carrier dynamics and provide a new strategy to optimize next-generation optoelectronic devices.