ACS Applied Materials & Interfaces
https://doi.org/10.1021/acsami.5c07597
Sangwoo Nam, Hanyeol Ahn, Beomjin Park, Minseon Gu, Hyun Su Park, Seungchul Choi,
Young Jun Chang, and Moonsup Han*
ABSTRACT: In this study, we demonstrate that a roomtemperature reactively sputtered aluminum oxynitride (AlOxNy) overlayer enables both effective doping and pronounced threshold voltage hysteresis in multilayer MoS2 FETs, while preserving fieldeffect mobility. Compared to conventional AlOx, the AlOxNy layer introduces trap states that are energetically aligned with the conduction band of MoS2, facilitating charge exchange across the heterointerface. Capacitance−voltage measurements confirm that nitrogen incorporation reduces the effective fixed charge density, enabling mobility-preserving operation without thermal annealing. Notably, the hysteresis window exhibits a marked expansion above ∼250 K, which correlates with the activation of out-of-plane phonon modes in MoS2. These phonons are proposed to assist in activating interfacial trap states within the AlOxNy layer, as supported by temperature-dependent electrical and spectroscopic analyses. While such trap-induced hysteresis may be undesirable for logic circuits, it offers valuable functionality for emerging device architecturessuch as in-memory computing and neuromorphic systemswhere hysteresis can be exploited. These findings underscore the potential of AlOxNy as a low-temperature-processable dielectric for 2D FETs and advance a new perspective on phonon-assisted interfacial charge modulation.
KEYWORDS: MoS2, neuromorphic computing, hysteresis, doping, trap states, interfacial interaction, temperature dependence, phonon
