A Gunn diode is disclosed which comprises a first contact layer (110), a second contact layer (120), and an active layer (130) based on a gallium nitride (GaN) semiconductor material having a base surface (132) and a side surface (135) 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 (110) electrically contacts the side surface (135) to form a side contact (115). The second contact layer (120) forms an electrical contact for the base surface (132), so that a maximum of the electric field strength is formed when an electric voltage is applied between the first contact layer (110) and the second contact layer (120) at the side contact (115).

The present invention provides a terahertz oscillator utilizing a GaN Gunn diode. A terahertz wave is generated in the active layer of the Gunn diode fabricated on GaN substrate. A GaN substrate is designed to act as a waveguide of the terahertz wave. Since the waveguide and the Gunn diodes are integrated, the terahertz wave generated in the active layer couples well with the waveguide made of the GaN substrates. The terahertz wave is emitted from the edge of the waveguide efficiently. To ensure high-reliability through reduction of radiation loss and mitigation of electromigration of anode metal, a GaN substrate with low dislocation density is used. The dislocation density of the GaN substrate is less than 1×10.sup.6 cm.sup.−2. Particularly, usage of a GaN substrate made by the ammonothermal method is preferred.

A negative differential resistance (NDR) device for non-volatile memory cells in crossbar arrays is provided. Each non-volatile memory cell is situated at a crosspoint of the array. Each non-volatile memory cell comprises a switching layer in series with an NDR material containing fast diffusive atoms that are electrochemically inactive. The switching layer is positioned between two elec-trodes.

The present invention provides a terahertz oscillator utilizing a GaN Gunn diode. A terahertz wave is generated in the active layer of the Gunn diode fabricated on GaN substrate. A GaN substrate is designed to act as a waveguide of the terahertz wave. Since the waveguide and the Gunn diodes are integrated, the terahertz wave generated in the active layer couples well with the waveguide made of the GaN substrates. The terahertz wave is emitted from the edge of the waveguide efficiently. To ensure high-reliability through reduction of radiation loss and mitigation of electromigration of anode metal, a GaN substrate with low dislocation density is used. The dislocation density of the GaN substrate is less than 1×10.sup.6 cm.sup.−2. Particularly, usage of a GaN substrate made by the ammonothermal method is preferred.

A composition of matter consisting primarily of a stabilizing element and a transition metal oxide, wherein the transition metal oxide is an anti-ferromagnetic Mott insulator with strong spin orbit interactions, and the composition of matter has a canted crystal structure.

An integrated neuron circuit structure comprising at least one thin-film resistor, one Metal Insulator Metal capacitor and one Negative Differential Resistance device.

A composition of matter consisting primarily of a stabilizing element and a transition metal oxide, wherein the transition metal oxide is an anti-ferromagnetic Mott insulator with strong spin orbit interactions, and the composition of matter has a canted crystal structure.

An integrated neuron circuit structure comprising at least one thin-film resistor, one Metal Insulator Metal capacitor and one Negative Differential Resistance device.

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.

Provided is a multi-negative differential resistance device. The multi-negative differential resistance device includes a first negative differential resistance device and a second negative differential resistance device connected in parallel with the first negative differential resistance device, and a peak and a valley of the first negative differential resistance device and a peak and a valley of the second negative differential resistance device are synthesized, and, thus, the multi-negative differential resistance device has two peaks and two valleys.