A vanadium dioxide (VO.sub.2)-based threshold switch device exhibiting current-controlled negative differential resistance (S-type NDR), an electrical oscillator circuit based on the threshold switch device, a wafer including a plurality of said devices, and a method of manufacturing said device are provided. The VO.sub.2-based threshold switch device exhibits volatile resistance switching and current-controlled negative differential resistance from the first time a sweeping voltage or voltage pulse is applied across the device without being treated with an electroforming process. Furthermore, the device exhibits substantially identical switching characteristics over at least 10.sup.3 switching operations between a high resistance state (HRS) and a low resistance state (LRS), and a plurality of threshold switch devices exhibits a threshold voltage V.sub.T spreading of less than about 25%. The threshold switch device may be included in an oscillator circuit to produce an astable oscillator that may serve as a functional building block in spiking-neuron based neuromorphic computing.

A Gunn diode is disclosed which comprises a first contact layer, a second contact layer, and an active layer based on a gallium nitride (GaN) semiconductor material having a base surface and a side surface non-parallel thereto. Optionally, related materials such as aluminum indium gallium nitride (AlInGaN) materials may also be used as the active layer. The first contact layer electrically contacts the side surface to form a side contact. The second contact layer forms an electrical contact for the base surface, so that a maximum of the electric field strength is formed when an electric voltage is applied between the first contact layer and the second contact layer at the side contact.

Examples herein relate to negative differential resistance devices. An example negative differential resistance device includes a first electrode and a first negative differential resistance device coupled to the first electrode. A second negative differential device is be coupled to the first negative differential resistance device. The second NDR device is different from the first NDR device. A second electrode is coupled to the second NDR device, and is electrically coupled with the first NDR device and the first electrode.

A tunneling barrier resistor includes a first electrode layer containing a first nonmagnetic iron-group-containing alloy layer which includes a first refractory metal, a second electrode layer containing a second nonmagnetic iron-group-containing alloy layer which includes a second refractory metal, and a first tunneling barrier dielectric layer located between the first electrode layer and the second electrode layer.

The present invention discloses a neuron and a neuromorphic system including the same. The neuron according to an embodiment of the present invention includes a metal insulator metal (MIM) device including a metal ion-doped insulating layer and configured to perform integration and fire, and the MIM device is formed to have a negative differential resistance (NDR) region in which current decreases as voltage increases.

The present invention discloses a neuron and a neuromorphic system including the same. The neuron according to an embodiment of the present invention includes a metal insulator metal (MIM) device including a metal ion-doped insulating layer and configured to perform integration and fire, and the MIM device is formed to have a negative differential resistance (NDR) region in which current decreases as voltage increases.