More Like this

1. Aqueous Oxidation of Biomass-Burning Furans by Singlet Molecular Oxygen ( ¹ O ₂ *)

   https://doi.org/10.1021/acs.est.4c10778  

   Arciva, Stephanie; Zhou, Yuejun; Jiang, Wenqing; Ross, Alicia; Zhang, Qi; Anastasio, Cort (June 2025, Environmental Science & Technology)
2. β -Ga ₂ O ₃ FinFETs with ultra-low hysteresis by plasma-free metal-assisted chemical etching

   https://doi.org/10.1063/5.0096490  

   Huang, Hsien-Chih; Ren, Zhongjie; Anhar Uddin Bhuiyan, A F; Feng, Zixuan; Yang, Zhendong; Luo, Xixi; Huang, Alex Q.; Green, Andrew; Chabak, Kelson; Zhao, Hongping; et al (August 2022, Applied Physics Letters)

   In this work, β-Ga 2 O 3 fin field-effect transistors (FinFETs) with metalorganic chemical vapor deposition grown epitaxial Si-doped channel layer on (010) semi-insulating β-Ga 2 O 3 substrates are demonstrated. β-Ga 2 O 3 fin channels with smooth sidewalls are produced by the plasma-free metal-assisted chemical etching (MacEtch) method. A specific on-resistance (R on,sp ) of 6.5 mΩ·cm 2 and a 370 V breakdown voltage are achieved. In addition, these MacEtch-formed FinFETs demonstrate DC transfer characteristics with near zero (9.7 mV) hysteresis. The effect of channel orientation on threshold voltage, subthreshold swing, hysteresis, and breakdown voltages is also characterized. The FinFET with channel perpendicular to the [102] direction is found to exhibit the lowest subthreshold swing and hysteresis. 

   more » « less
3. H trapping at the metastable cation vacancy in α -Ga ₂ O ₃ and α -Al ₂ O ₃

   https://doi.org/10.1063/5.0094707  

   Venzie, Andrew; Portoff, Amanda; Stavola, Michael; Fowler, W. Beall; Kim, Jihyun; Jeon, Dae-Woo; Park, Ji-Hyeon; Pearton, Stephen J. (May 2022, Applied Physics Letters)

   α-Ga₂O₃has the corundum structure analogous to that of α-Al₂O₃. The bandgap energy of α-Ga₂O₃is 5.3 eV and is greater than that of β-Ga₂O₃, making the α-phase attractive for devices that benefit from its wider bandgap. The O–H and O–D centers produced by the implantation of H⁺and D⁺into α-Ga₂O₃have been studied by infrared spectroscopy and complementary theory. An O–H line at 3269 cm⁻¹is assigned to H complexed with a Ga vacancy (V_Ga), similar to the case of H trapped by an Al vacancy (V_Al) in α-Al₂O₃. The isolated V_Gaand V_Aldefects in α-Ga₂O₃and α-Al₂O₃are found by theory to have a “shifted” vacancy-interstitial-vacancy equilibrium configuration, similar to V_Gain β-Ga₂O₃, which also has shifted structures. However, the addition of H causes the complex with H trapped at an unshifted vacancy to have the lowest energy in both α-Ga₂O₃and α-Al₂O₃. 

   more » « less
4. Greatly Enhanced Radiative Transfer Enabled by Hyperbolic Phonon Polaritons in α ‐MoO ₃

   https://doi.org/10.1002/adfm.202403719  

   Chen, Yikang; Pacheco, Mauricio_A_Segovia; Salihoglu, Hakan; Xu, Xianfan (May 2024, Advanced Functional Materials)

   Abstract Orthorhombic molybdenum trioxide (α‐MoO₃) is a highly anisotropic hyperbolic material in nature. Within its wide Reststrahlen bands, α‐MoO₃has hyperboloidal dispersion that supports bulk propagation of high‐k phonon polariton modes. These modes can serve as energy transport channels to greatly enhance radiative heat transfer inside the material. In this work, large radiative transfer enabled by phonon polaritons in α‐MoO₃is demonstrated. The study first determines the temperature‐dependent permittivity of α‐MoO₃from polarized Fourier‐Transform Infrared (FTIR) spectroscopy measurements and then uses a many‐body radiative heat transfer model to predict the equivalent radiative thermal conductivity of hyperbolic phonon polariton. Contribution of radiative transfer to the total thermal transport is experimentally determined from the Time‐Domain Thermoreflectance (TDTR) measurements in a temperature range from −100 to 300 °C. It is found that radiative transfer can account for ≈60% of the total thermal transport at a temperature of 300 °C. That is, conductive thermal transport is enhanced by >100% by radiative transfer, or radiation inside α‐MoO₃is greater than that of conduction. These additional energy pathways will have important implications in thermal management in new materials and devices. 

   more » « less
5. The anisotropic quasi-static permittivity of single-crystal β -Ga ₂ O ₃ measured by terahertz spectroscopy

   https://doi.org/10.1063/5.0031464  

   Gopalan, Prashanth; Knight, Sean; Chanana, Ashish; Stokey, Megan; Ranga, Praneeth; Scarpulla, Michael A.; Krishnamoorthy, Sriram; Darakchieva, Vanya; Galazka, Zbigniew; Irmscher, Klaus; et al (December 2020, Applied Physics Letters)

   null (Ed.)