Spalling-Induced Liftoff and Transfer of Electronic Films Using a van der Waals Release Layer.

Heterogeneous integration strategies are increasingly being employed to achieve more compact and capable electronics systems for multiple applications including space, electric vehicles, and wearable and medical devices. To enable new integration strategies, the growth and transfer of thin electronic films and devices, including III-nitrides, metal oxides, and 2D materials, using 2D boron nitride (BN)-on-sapphire templates are demonstrated. The van der Waals (vdW) BN layer, in this case, acts as a preferred mechanical release layer for precise separation at the substrate-film interface and leaves a smooth surface suitable for vdW bonding.

Influence of field conditions on quantitative analysis of single crystal thorium dioxide by atom probe tomography.

Atom probe tomography (APT), a 3D microscopy technique, has great potential to reveal atomic scale compositional variations, such as those associated with irradiation damage. However, obtaining accurate compositional quantification by APT for high bandgap materials is a longstanding challenge, given the sensitivity to field evaporation parameters and inconsistent behaviors across different oxides. This study investigates the influence of APT laser energy and specimen base temperature on compositional accuracy in single crystal thoria (ThO).

Two-dimensional BN buffer for plasma enhanced atomic layer deposition of AlO gate dielectrics on graphene field effect transistors.

Here, we investigate the use of few-layer metal organic chemical vapor deposition (MOCVD) grown BN as a two-dimensional buffer layer for plasma enhanced atomic layer deposition (PE-ALD) of AlO on graphene for top gated field effect transistors (FETs). The reactive nature of PE-ALD enables deposition of thin (2 nm) dielectrics directly on graphene and other two-dimensional materials without the need for a seed or functionalization layer; however, this also leads to significant oxidation of the graphene layer as observed by Raman. In FETs, we find this oxidation destroys conductivity in the graphene channel.

A Computational and Experimental Investigation of the Phonon and Optical Properties of Au₂P₃.

In a combined experimental and theoretical study of gold phosphide (Au₂P₃), we investigate its vibrational properties, band structure, and dielectric properties, providing new insight into the properties of this underexplored material. Using a simple synthesis route, Au₂P₃ thin films were produced, enabling the first reported Raman analysis of this material. Coupled with first-principles calculations of these Raman modes, this analysis reveals that low-frequency vibrations are due to Au or mixed Au to P, and at higher frequencies, they are due to P vibrations.

Wafer scale BN on sapphire substrates for improved graphene transport.

Wafer scale (2") BN grown by metal organic chemical vapor deposition (MOCVD) on sapphire was examined as a weakly interacting dielectric substrate for graphene, demonstrating improved transport properties over conventional sapphire and SiO/Si substrates. Chemical vapor deposition grown graphene was transferred to BN/sapphire substrates for evaluation of more than 30 samples using Raman and Hall effects measurements. A more than 2x increase in Hall mobility and 10x reduction in sheet carrier density was measured for graphene on BN/sapphire compared to sapphire substrates.

Flexible Gallium Nitride for High-Performance, Strainable Radio-Frequency Devices.

Flexible gallium nitride (GaN) thin films can enable future strainable and conformal devices for transmission of radio-frequency (RF) signals over large distances for more efficient wireless communication. For the first time, strainable high-frequency RF GaN devices are demonstrated, whose exceptional performance is enabled by epitaxial growth on 2D boron nitride for chemical-free transfer to a soft, flexible substrate. The AlGaN/GaN heterostructures transferred to flexible substrates are uniaxially strained up to 0.