Topological Quantum Switching Enabled Neuroelectronic Synaptic Modulators for Brain Computer Interface.

Aging and genetic-related disorders in the human brain lead to impairment of daily cognitive functions. Due to their neural synaptic complexity and the current limits of knowledge, reversing these disorders remains a substantial challenge for brain-computer interfaces (BCI). In this work, a solution is provided to potentially override aging and neurological disorder-related cognitive function loss in the human brain through the application of the authors' quantum synaptic device.

Metal-Induced Trap States: The Roles of Interface and Border Traps in HfO/InGaAs.

By combining capacitance-voltage measurements, TCAD simulations, and X-ray photoelectron spectroscopy, the impact of the work function of the gate metals Ti, Mo, Pd, and Ni on the defects in bulk HfO and at the HfO/InGaAs interfaces are studied. The oxidation at Ti/HfO is found to create the highest density of interface and border traps, while a stable interface at the Mo/HfO interface leads to the smallest density of traps in our sample. The extracted values of D of 1.

Impact of an Underlying 2DEG on the Performance of a p-Channel MOSFET in GaN.

The influence of an underlying 2-dimensional electron gas (2DEG) on the performance of a normally off p-type metal oxide semiconductor field effect transistor (MOSFET) based on GaN/AlGaN/GaN double heterojunction is analyzed via simulations. By reducing the concentration of the 2DEG, a greater potential can be dropped across the GaN channel, resulting in enhanced electrostatic control. Therefore, to minimize the deleterious impact on the on-state performance, a composite graded back-to-back AlGaN barrier that enables a trade-off between n-channel devices and Enhancement-mode (E-mode) p-channel is investigated.

Quantum Topological Neuristors for Advanced Neuromorphic Intelligent Systems.

Neuromorphic artificial intelligence systems are the future of ultrahigh performance computing clusters to overcome complex scientific and economical challenges. Despite their importance, the advancement in quantum neuromorphic systems is slow without specific device design. To elucidate biomimicking mammalian brain synapses, a new class of quantum topological neuristors (QTN) with ultralow energy consumption (pJ) and higher switching speed (µs) is introduced.

Origins of the Schottky Barrier to a 2DHG in a Au/Ni/GaN/AlGaN/GaN Heterostructure.

We report the influence of thickness of an undoped GaN (u-GaN) layer on current transport to a 2DHG through the metal/p++GaN contact in a GaN/AlGaN/GaN heterostructure. The current is dominated by an internal potential barrier of 0.2-0.

Negative Capacitance beyond Ferroelectric Switches.

Negative capacitance transistors are a unique class of switches capable of operation beyond the Boltzmann limit to realize subthermionic switching. To date, the negative capacitance effect has been predominantly attributed to devices employing an unstable insulator with ferroelectric properties, exhibiting a two-well energy landscape, in accordance with the Landau theory. The theory and operation of a solid electrolyte field effect transistor (SE-FET) of subthreshold swing less than 60 mV/dec in the absence of a ferroelectric gate dielectric are demonstrated in this work.

Diffusion-Controlled Faradaic Charge Storage in High-Performance Solid Electrolyte-Gated Zinc Oxide Thin-Film Transistors.

An electrochemical device capable of manifesting reversible charge storage at the interface of an active layer offers formidable advantages, such as low switching energy and long retention time, in realizing synaptic behavior for ultralow power neuromorphic systems. Contrary to a supercapacitor-based field-effect device that is prone to low memory retention due to fast discharge, a solid electrolyte-gated ZnO thin-film device exhibiting a battery-controlled charge storage mechanism via mobile charges at its interface with tantalum oxide is demonstrated. Analysis via cyclic voltammetry and chronoamperometry uniquely distinguishes the battery behavior of these devices, with an electromotive force generated due to polarization of charges strongly dependent on the scan rate of the applied voltage.

Nanoionics-Based Three-Terminal Synaptic Device Using Zinc Oxide.

Artificial synaptic thin film transistors (TFTs) capable of simultaneously manifesting signal transmission and self-learning are demonstrated using transparent zinc oxide (ZnO) in combination with high κ tantalum oxide as gate insulator. The devices exhibit pronounced memory retention with a memory window in excess of 4 V realized using an operating voltage less than 6 V. Gate polarity induced motion of oxygen vacancies in the gate insulator is proposed to play a vital role in emulating synaptic behavior, directly measured as the transmission of a signal between the source and drain (S/D) terminals, but with the added benefit of independent control of synaptic weight.