arXiv subjects

Phillip R. Jahelka

Publications and source records attributed to Phillip R. Jahelka.

2 recordsLinked to original sources

arXiv2025

Spalled barium titanate single crystal thin films for functional device applications

We report a scalable approach for fabricating single-crystal barium titanate (BTO) thin films through spalling from bulk substrates. Conventional thin film growth techniques often face challenges in achieving high-quality single crystal microstructure over large areas, resulting in reduced performance in functional devices. In contrast, spalling - i.e., performing stress-induced exfoliation of bulk single crystals - enables the separation of single crystal thin films with controllable thicknesses ranging from 100 nm to 15 um and lateral dimensions up to several millimeters. Electro-optic characterization of the spalled films yields a Pockels coefficient of r33 = 55 pm/V in multi-domain regions and 160 pm/V in single-domain regions, leading to projections up to 1980 pm/V for r42 under conditions of unclamped excitation. Our results indicate that spalled BTO single-crystal thin films preserve bulk electro-optic properties and exceed the performance of commercially available thin-film lithium niobate, making them suitable for integration in advanced photonic and optoelectronic devices.

physics.app-ph↗

arXiv2019

A new metal transfer process for van der Waals contacts to vertical Schottky-junction transition metal dichalcogenide photovoltaics

Two-dimensional transition metal dichalcogenides are promising candidates for ultrathin optoelectronic devices due to their high absorption coefficients and intrinsically passivated surfaces. To maintain these near-perfect surfaces, recent research has focused on fabricating contacts that limit Fermi-level pinning at the metal-semiconductor interface. Here, we develop a new, simple procedure for transferring metal contacts that does not require aligned lithography. Using this technique, we fabricate vertical Schottky-junction $WS_2$ solar cells with Ag and Au as asymmetric work function contacts. Under laser illumination, we observe rectifying behavior and open-circuit voltage above 500 mV in devices with transferred contacts, in contrast to resistive behavior and open-circuit voltage below 15 mV in devices with evaporated contacts. One-sun measurements and device simulation results indicate that this metal transfer process could enable high-specific-power vertical Schottky-junction transition metal dichalcogenide photovoltaics, and we anticipate that this technique will lead to advances for two-dimensional devices more broadly.

physics.app-ph↗