Elastocapillary Force Induced Alignment of Large Area Planar Nanowires.

Achieving large scale precise positioning of the vapor-liquid-solid (VLS) nanowires is one of the biggest challenges for mass production of nanowire-based devices. Although there have been many noteworthy progresses in postgrowth nanowire alignment method development over the past few decades, these methods are mostly suitable for low density applications only. For high density applications such as transistors, both high yield and density are required.

Transferrable AlGaN/GaN High-Electron Mobility Transistors to Arbitrary Substrates via a Two-Dimensional Boron Nitride Release Layer.

Mechanical transfer of high-performing thin-film devices onto arbitrary substrates represents an exciting opportunity to improve device performance, explore nontraditional manufacturing approaches, and paves the way for soft, conformal, and flexible electronics. Using a two-dimensional boron nitride release layer, we demonstrate the transfer of AlGaN/GaN high-electron mobility transistors (HEMTs) to arbitrary substrates through both direct van der Waals bonding and with a polymer adhesive interlayer. No device degradation was observed because of the transfer process, and a significant reduction in device temperature (327-132 °C at 600 mW) was observed when directly bonded to a silicon carbide (SiC) wafer relative to the starting wafer.

High Aspect Ratio β-GaO Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching.

β-GaO, with a bandgap of ∼4.6-4.9 eV and readily available bulk substrates, has attracted tremendous interest in the wide bandgap semiconductor community.

In situ transmission electron microscopy of transistor operation and failure.

Microscopy is typically used as a post-mortem analytical tool in performance and reliability studies on nanoscale materials and devices. In this study, we demonstrate real time microscopy of the operation and failure of AlGaN/GaN high electron mobility transistors inside the transmission electron microscope. Loading until failure was performed on the electron transparent transistors to visualize the failure mechanisms caused by self-heating.

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.

Incomplete Ionization of a 110 meV Unintentional Donor in β-GaO and its Effect on Power Devices.

Understanding the origin of unintentional doping in GaO is key to increasing breakdown voltages of GaO based power devices. Therefore, transport and capacitance spectroscopy studies have been performed to better understand the origin of unintentional doping in GaO. Previously unobserved unintentional donors in commercially available [Formula: see text] GaO substrates have been electrically characterized via temperature dependent Hall effect measurements up to 1000 K and found to have a donor energy of 110 meV.

High-Speed Planar GaAs Nanowire Arrays with fmax > 75 GHz by Wafer-Scale Bottom-up Growth.

Wafer-scale defect-free planar III-V nanowire (NW) arrays with ∼100% yield and precisely defined positions are realized via a patterned vapor-liquid-solid (VLS) growth method. Long and uniform planar GaAs NWs were assembled in perfectly parallel arrays to form double-channel T-gated NW array-based high electron mobility transistors (HEMTs) with DC and RF performance surpassing those for all field-effect transistors (FETs) with VLS NWs, carbon nanotubes (CNTs), or graphene channels in-plane with the substrate. For a planar GaAs NW array-based HEMT with 150 nm gate length and 2 V drain bias, the on/off ratio (ION/IOFF), cutoff frequency (fT), and maximum oscillation frequency (fmax) are 10(4), 33, and 75 GHz, respectively.