Terahertz Gunn oscillator using gallium nitride
AssigneeSixPoint Materials, Inc.
InventorTadao Hashimoto
Life of this patent
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Abstract
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 1×106 cm−2. Particularly, usage of a GaN substrate made by the ammonothermal method is preferred.
Claims19
A terahertz oscillator to generate a terahertz wave of a wavelength λ in air between 0.1 mm and 1 mm, comprising a Gunn diode comprising a GaN substrate having n-type conduction, an anode contact on a first major side of the GaN substrate, and the Gunn diode is configured to emit a terahertz wave formed on a second major side of the GaN substrate, wherein:
- the GaN substrate forms a slab waveguide having first and second lateral boundaries and having first and second termination edges, with the GaN substrate having a longitudinal dimension of L in a longitudinal direction, lateral dimension of W, and thickness of T;
- the Gunn diode emits the terahertz wave in the slab waveguide;
- and the slab waveguide is configured to conduct the terahertz wave along the longitudinal direction, and to emit the terahertz wave at first and second termination edges of the slab waveguide during operation, wherein the Gunn diode further comprises a contact layer of n+-GaN on a top of the active layer, a passivation layer with a contact hole on the contact layer, and a portion of the metal cathode contact in the contact hole, wherein the cross-sectional area of the contact hole is smaller than 0.01 mm2.
A terahertz oscillator to generate a terahertz wave of a wavelength λ in air between 0.1 mm and 1 mm, comprising a Gunn diode comprising a GaN substrate having n-type conduction, an anode contact on a first major side of the GaN substrate, and the Gunn diode is configured to emit a terahertz wave formed on a second major side of the GaN substrate, wherein:
- the GaN substrate forms a slab waveguide having first and second lateral boundaries and having first and second termination edges, with the GaN substrate having a longitudinal dimension of L in a longitudinal direction, lateral dimension of W, and thickness of T;
- the Gunn diode emits the terahertz wave in the slab waveguide;
- and the slab waveguide is configured to conduct the terahertz wave along the longitudinal direction, and to emit the terahertz wave at first and second termination edges of the slab waveguide during operation, wherein the Gunn diode further comprises a contact layer of n+-GaN on a top of the active layer, and the active layer and the contact layer have a mesa shape formed by etching the active layer and the contact layer, and further comprising a passivation layer covering the exposed surface except for the top surface of the contact layer and having a contact hole through the passivation layer, and a portion of the metal cathode extending through the contact hole and in contact with the n+-contact layer, wherein the cross-sectional area of the contact hole is smaller than 0.01 mm2.
A terahertz oscillator to generate a terahertz wave of a wavelength λ in air between 0.1 mm and 1 mm, comprising a Gunn diode comprising a GaN substrate having n-type conduction, an anode contact on a first major side of the GaN substrate, and the Gunn diode is configured to emit a terahertz wave formed on a second major side of the GaN substrate, wherein:
- the GaN substrate forms a slab waveguide having first and second lateral boundaries and having first and second termination edges, with the GaN substrate having a longitudinal dimension of L in a longitudinal direction, lateral dimension of W, and thickness of T;
- the Gunn diode emits the terahertz wave in the slab waveguide;
- and the slab waveguide is configured to conduct the terahertz wave along the longitudinal direction, and to emit the terahertz wave at first and second termination edges of the slab waveguide during operation, wherein the metal cathode contact is mounted on a conductive base with a metal bond and the thickness of the GaN substrate is such that a volume of the GaN substrate through which electric current flows acts as a vertical antenna during use, and wherein the conductive base further comprises a wave reflector adjacent to one side of the first termination edge.
Dependencies are inferred from the claim text.