Peide Ye

Real-space structural chirality is known to engender a range of exotic electronic effects including Kramers-Weyl fermions and chirality-induced spin selectivity (CISS). Tellurium (Te) is an elemental semiconductor with a distinct chiral crystal structure. A unidirectional magnetoresistance (MR) was reported in single-crystalline Te nanowires, which was interpreted as evidence for chirality-induced charge-to-spin conversion [1]. The nanowire morphology limited the measurements to a single collinear configuration of bias current and crystalline helical axis. Using hydrothermal growth, we have obtained high-quality single-crystal nanoplates of Te with 10s of mm in dimensions. The Te nanoplates were patterned into “L”-bar devices, which facilitated a comprehensive set of MR measurements, encompassing all combinations of the current and magnetic field directions in relation to the chiral crystal axis on a single device …

The observation of anomalous quantum Hall and Shubnikov-de Haas (SdH) oscillation sequences, wherein Landau level energy exhibits a proportionality to the square root of the applied external magnetic field, has opened up new avenues of research into relativistic Fermions. This contrasts conventional Landau levels, where energy increases linearly with the external magnetic field. In this study, we investigate Landau levels in a novel class of topological materials characterized by Weyl-type spin-orbital coupling bands, focusing on the 2D Tellurium (Te) conduction band. Here, the Landau-level energy takes on the form E n= nhω c/2π±√ 4πneBλ 2/h (n≥ 0), with λ representing the spin-orbit coupling parameter. By carefully tuning both the chemical potential and the magnetic field, we experimentally observed a unique Landau-level spectrum. Notably, the presence of two Fermi surfaces, distinguished by different …

The low thermal conductivity of β-Ga 2 O 3 is a significant concern for maximizing the potential of this ultra-wide bandgap semiconductor as a power switching device technology. Here, we report on the use of nanocrystalline diamond (NCD) deposited via microwave plasma enhanced chemical vapor deposition (MP-CVD) as a top-side, device-level thermal management solution on a lateral β-Ga 2 O 3 transistor. NCD was grown via MP-CVD on β-(Al x Ga 1− x) 2 O 3/β-Ga 2 O 3 heterostructures prior to the gate formation of the field-effect transistor. A reduced growth temperature of 400 C and a SiN x barrier layer were used to protect the oxide semiconductors from etching in the MP-CVD H 2 plasma environment. Raman spectroscopy showed a highly sp 3-bonded NCD film was obtained at 400 C, with grain size of about 50–100 nm imaged via atomic force microscopy. The incorporation of the NCD heat-spreading …

Amorphous oxide semiconductor transistors have been a mature technology in display panels for upward of a decade, and have recently been considered as promising back‐end‐of‐line compatible channel materials for monolithic 3D applications. However, achieving high‐mobility amorphous semiconductor materials with comparable performance to traditional crystalline semiconductors has been a long‐standing problem. Recently it has been found that greatly reducing the thickness of indium oxide, enabled by an atomic layer deposition (ALD) process, can tune its material properties to achieve high mobility, high drive current, high on/off ratio, and enhancement‐mode operation at the same time, beyond the capabilities of conventional oxide semiconductor materials. In this work, the history leading to the re‐emergence of indium oxide, its fundamental material properties, growth techniques with a focus on ALD …

As transistor dimensions reach the 3-nm node, interface and surface engineering emerges as critical considerations. Challenges introduced by reduced conductivity and mobility due to surface depletion significantly impact thickness scaling and contact performance. In this work, we report the surface accumulation in atomic layer deposition (ALD) grown In O thin-film transistors (TFTs). The negative Schottky barrier enables an ultralow metal-to-semiconductor contact resistance of at electron charge density in a nanometer ultrathin In O channel. The effect of film thickness and annealing on contact resistance is investigated. Ultralow contact resistivity and current transfer length are achieved in a 1-nm-thick film. The superior ohmic contact is made possible by the charge neutrality level (CNL) deeply aligned inside the conduction band for In O . Together with theoretical …

Tellurium has a chiral helical structure, which breaks the inversion symmetry and results in a momentum-dependent radial spin texture at the Fermi level. With a charge current applied along the chirality direction, the Fermi level will be shifted and spins of electrons will be polarized either parallel or anti-parallel to the current direction depending on the handedness of the Te chirality. We are studying this chirality-induced spin polarizations by using spin-torque ferromagnetic resonance to observe the spin-orbit torques generated from single-crystalline Te flakes. We deposited a 10-nm Permalloy (Py; Ni 80 Fe 20) layer and used ion-milling and lithography to integrate Te/Py heterostructure into a coplanar waveguide for radio frequency (rf) measurements. We then applied GHz rf currents through Te/Py devices and collect a dc mixing voltage (V mix) due to the mixing of anisotropic magnetoresistance of Py and rf current …

The reliability of a β-Ga2O3 thin-film field-effect transistor is investigated under positive-bias stress (PBS). The transistor has a tri-gate structure with a gate dielectric of Al2O3. By characterizing low-frequency noise (LFN), the spatial distribution of trap in the gate dielectric was quantitatively extracted. The measured power spectral density (PSD) followed a 1/f-shape due to trapping and de-trapping of the channel carriers to and from the gate dielectric. Notably, the vertical distribution of the traps perpendicular to the interface of β-Ga2O3 and Al2O3 was mapped.

G23. 00006: Strong spin-orbit-interaction probed by weak antilocalization in p-type 2D Te under pressure*