Ferroelectric α‐In₂Se₃ Wrapped‐Gate β‐Ga₂O₃ Field‐Effect Transistors for Dynamic Threshold Voltage Control

Abstract

Indium selenide (α‐In2Se3), which is a recently emerging ferroelectric semiconductor, can solve a major hindrance to applications of an ultra‐wide bandgap beta‐gallium oxide (β‐Ga2O3) semiconductor. Here, ferroelectric α‐In2Se3 wrapped‐gate β‐Ga2O3 field‐effect transistors (FETs) for dynamic threshold voltage (VTH) control is demonstrated. The dry‐transferred α‐In2Se3 layer is wrapped around β‐Ga2O3 channel, which allows efficient electrostatic gate modulation. Thus, the ferroelectricity of α‐In2Se3 and a thin native oxide interlayer formed at the interface between β‐Ga2O3 and α‐In2Se3 can provide effective VTH control. Applying a positive voltage pulse to the gate electrode induces positive VTH shift; hence, the device can be even changed from depletion to enhancement (E‐) mode. The E‐mode β‐Ga2O3 FET exhibits steep‐subthreshold slope with a negligible hysteresis. The VTH of E‐mode can be further modulated by applying back‐gate bias, and electrical performance can be enhanced via dual‐gate operation. The approach demonstrates an energy efficient β‐Ga2O3‐based switching device architecture integrated with ferroelectric van der Waals 2D materials.

An artificial neuromuscular junction for enhanced reflexes and oculomotor dynamics based on a ferroelectric CuInP 2 S 6 /GaN HEMT

“…The direct actuation of the mechanical platform using the artificial NMJ provides a wide range of neuromorphic sensing-to-action applications, including time-offlight ranging (38)(39)(40)(41)(42)(43), in-sensor/near-sensor computing (44)(45)(46)(47)(48), and human-computer interaction (49). In this study, we achieved a normalized output current of 200 mA/mm with the CIPS/GaN FeHEMT, which is notably greater than that of recently reported synaptic transistors (for more details, see table S1) (50)(51)(52)(53)(54)(55)(56)(57)(58)(59). Therethe CIPS/GaN FeHEMT is potentially deployable as an artificial NMJ in robotic systems to operate mechanical actuators that require a milliampere-scale driving current for macro-motion.…”

Reconfigurable Physical Reservoir in GaN/α-In2Se3 HEMTs Enabled by Out-of-Plane Local Polarization of Ferroelectric 2D Layer

“…The 2DEG was depleted when the ferroelectric polarization was contrary to the polarization of the AlGaN barrier layer (yellow arrows in Figure a). We performed TCAD (Synopsys Corp.) simulation using an experimentally calibrated model before and after the etching process to verify the effect of polarization concentration, as shown in Figure f and g. The bandgap energies of GaN, AlGaN, Al 2 O 3 , and α-In 2 Se 3 utilized for TCAD simulation are 3.4, 4.0, 6.4, and 1.39 eV, respectively; furthermore, corresponding electron affinities are 4.1, 4.6, 1.35, and 3.6 eV. − The arrows in Figure f and g indicate the vectors of the total polarization in α-In 2 Se 3 , whereas the color chart shows the magnitude of the lateral polarization. The simulation confirmed that lateral polarization was suppressed when the α-In 2 Se 3 layer was self-aligned with the gate metal, while the total polarization was preserved.…”

Vertically Stacked vdW Double Heterojunction Photodiode with Ultrawide Bandgap Gallium Oxide Electron Reservoir

“…where W tip is the work function of the tip and P KPFM is the measured potential, [30] Figure S3, Supporting Information. The work functions of WSe 2 and Ga 2 O 3 were measured to be 4.85 and 4.06 eV, respectively.…”