Phillip Dobson | Searcharxiv

arXiv2026

Direct Nanoscale Pyroelectric Characterization of a CuInP${}_2$S${}_6$ van der Waals Nanogenerator

Pyroelectric energy conversion offers a route for harvesting time-dependent thermalfluctuations that are abundant in natural and technological environments. Twodimensional ferroelectrics are particularly attractive for this purpose because reduced dimensionality enables ultrathin, mechanically compliant device architectures. Here, we demonstrate direct nanoscale pyroelectric characterization of an out-of-plane van der Waals nanogenerator based on CuInP2S6 (CIPS) encapsulated between few-layer graphene electrodes. A scanning thermal microscopy (SThM) probe is employed as a localized nanoscale heat source while the electrically generated response is measured in situ through the device electrodes. Harmonic detection isolates the pyroelectric signal from parasitic first-harmonic electromechanical contributions, while finite-element thermal modeling combined with probe calibration enables direct determination of the local pyroelectric coefficient from the measured electrical response. Beyond quantitative characterization, the spatially resolved measurements directly identify electrically inactive regions associated with device defects, revealing local performance-limiting features that remain hidden in conventional spatially averaged pyroelectric measurements. The presented approach establishes a versatile platform for quantitative nanoscale pyroelectric characterization and the optimization of van der Waals pyroelectric devices.

cond-mat.mes-hall↗

arXiv2025

Characterization of heat transfer in 3D CMOS structures using Sideband Scanning Thermal Wave Microscopy

Efficient thermal management is critical for cryogenic CMOS circuits, where local heating can compromise device performance and qubit coherence. Understanding heat flow at the nanoscale in these multilayer architectures requires localized, high-resolution thermal probing techniques capable of accessing buried structures. Here, we introduce a sideband thermal wave detection scheme for Scanning Thermal Microscopy, S-STWM, to probe deeply buried heater structures within CMOS dies. By extracting the phase of propagating thermal waves, this method provides spatially resolved insight into heat dissipation pathways through complex multilayer structures. Our approach enables quantitative evaluation of thermal management strategies, informs the design of cryo-CMOS circuits, and establishes a foundation for in situ thermal characterization under cryogenic operating conditions.

cond-mat.other↗