Mr. Michael Uzhansky - Ph.D. Candidate
01/02/2026
אודיטוריום ע"ש דויד וואנג, בניין מידן, קומה 3
13:30
Atomically thin two-dimensional (2D) van der Waals (vdW) ferroelectrics, combining strong light–matter interactions with electrically tunable electrostatics, enable programmable optoelectronic functionalities beyond permanently doped junctions. Here, two device concepts are described that utilize ferroelectricity in 2D α-In₂Se₃ to realize reconfigurable, low-power optoelectronic elements with nonvolatile operation, paving the way for energy-efficient sensing and memory.
First, I demonstrate a ferroelectric-actuated WSe₂/α-In₂Se₃ asymmetric heterostructure, where the in-plane polarization of α-In₂Se₃ induces micron-scale, non-volatile electrostatic doping in ambipolar WSe₂. This enables stable p–n n–p switching with a rectification ratio of ~10⁶ and ultra-low leakage current of ≈10⁻¹² A. Under illumination, the same junction exhibits a switchable photovoltaic response (VOC ≈ 0.5 V, ISC ≈ 1.1 nA, fill factor ≈0.6; η≈0.51% with a projected increase up to ≈3.6%), enabling self-powered, non-volatile readout through the polarity of the photovoltaic short-circuit current and multi-level states.
Second, I show direct pyroelectric–photovoltaic measurements in α-In₂Se₃ field-effect devices, revealing a giant pyroelectric coefficient of ≈30.7 mC m⁻² K⁻¹ and a figure of merit of ≈135.9 m² C⁻¹. I uncover a coupled effect where pyroelectric current follows dT/dt while photocurrent linearly follows temperature, and I realize a self-powered photovoltaic memory with ~10³ ON/OFF current ratio.
Together, these results establish 2D ferroelectric vdW platforms as monolithic building blocks for integrated light/heat sensing, energy harvesting, and in-memory optoelectronic logic.