# US 7,609,208 B2 · Electrodes on a photoconductive substrate for generation and detection of terahertz radiation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,208 B2 - Document ID: US7609208B2 - Status: Granted - Kind: B2 - Application number: 10/526,556 - Filed: 2003-09-04 - Published: 2006-07-13 - Granted: 2009-10-27 - Earliest claimed: 2002-09-04 - Assignees: TeraView Limited - Inventors: Michael J. Evans; William R. Tribe - Web page: https://patentgrep.com/patent/US7609208B2 ## CPC - H01S 1/02: solid - H01Q 3/2676: {Optically controlled phased array} - H10F 30/10: the devices being sensitive to infrared radiation, visible or ultraviolet radiation, and having no potential barriers, e.g. photoresistors - H10F 77/124: comprising only Group III-V materials, e.g. GaAs - H10F 77/20: Electrodes - Y02E 10/544: Solar cells from Group III-V materials - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract An antenna comprising a photoconductive material (61) and a plurality of spaced apart electrodes (69, 71) provided on said photoconductive material (61), each electrode (69, 71) having at least one facing edge which faces a facing edge of an adjacent electrode, a physical barrier (67) being provided abutting a facing edge of at least one electrode (69, 71), said barrier (67) extending to at least the full height of said facing edge. ## Claims ### Claim 1 An antenna comprising a layer of a single photoconductive material and a plurality of spaced apart electrodes provided on said photoconductive material layer, each electrode having at least one facing edge which faces a facing edge of an adjacent electrode, a physical barrier being provided abutting a facing edge of at least one electrode, said barrier extending to at least the full height of said facing edge, wherein the facing edge of the at least one electrode is provided within a recess of the surface of said layer of photoconductive material such that said barrier is formed from said single photoconductive material, said recess including side-walls formed from said photoconductive material, and one of said side-walls of said recess providing said barrier. ### Claim 2 (depends on 1) An antenna according to claim 1, wherein the facing edges of adjacent electrodes are provided within recesses, such that the side walls of said recesses provides the barriers for both facing edges, and wherein said photoconductive material is provided between said adjacent facing edges. ### Claim 3 (depends on 1) An antenna according to claim 1, wherein said sidewalls extend to at least the full height of said facing edge. ### Claim 4 (depends on 3) An antenna according to claim 3, wherein a capping material is provided over said electrodes. ### Claim 5 (depends on 4) An antenna according to claim 4, wherein said capping material is an antireflective material. ### Claim 6 (depends on 4) An antenna according to claim 4, wherein said capping material comprises silicon nitride, silicon dioxide, silicon monoxide, photoresist, polymide or acrylics. ### Claim 7 (depends on 1) An antenna according to claim 1, wherein a capping material is provided over at least a part of the facing edges such that said capping material and the sidewalls of said recess form said barrier. ### Claim 8 (depends on 1) An antenna according to claim 1, wherein the height of the side walls exceeds the height of the said facing edge by at most twice the penetration depth of the radiation used to excite the antenna, in the photoconductive material. ### Claim 9 (depends on 1) An antenna according to claim 1, wherein the height of the side walls exceeds the height of the said facing edge by at most the penetration depth of the radiation used to excite the antenna, in the photoconductive material. ### Claim 10 (depends on 1) An antenna according to claim 1, wherein the height of the sidewalls exceeds the height of the facing edge by at most 1 μm. ### Claim 11 (depends on 1) An antenna according to claim 1, wherein the electrodes are provided on a planar surface of said photoconductive material and a capping material is provided on the facing edges of said electrodes such that said capping material forms said barrier. ### Claim 12 (depends on 1) An antenna according to claim 1, wherein two electrodes are provided in a ‘bow-tie ’ configuration, each electrode having a triangular portion and being arranged such the apexes of said triangular portion face each other and are spaced apart, said facing edges being provided by said apexes. ### Claim 13 (depends on 1) An antenna according to claim 1, wherein two electrodes comprise a plurality of elongate fingers, provided in an interdigitated arrangement with the facing edges being provided by the elongate edges of adjacent fingers. ### Claim 14 (depends on 13) An antenna according to claim 13, wherein the gap between the facing edges is at most 100 μm. ### Claim 15 (depends on 1) An antenna according to claim 1, wherein the gap between facing edges is at most 100 μm. ### Claim 16 (depends on 1) An antenna according to claim 1, wherein the photoconductive material comprises a least one selected from LT-GaAs, LT AlGaAs, As-GaAs or LT-InGaAs. ### Claim 17 (depends on 1) An antenna according to claim 1, wherein said electrodes comprise at least one selected from Gold, Aluminium, Titanium, NiCr or Pd. ### Claim 18 (depends on 1) An antenna according to claim 1, further comprising biasing means configured to apply a bias between facing edges of adjacent electrodes, said biasing means being configured to bias the electrodes such that the current density at their facing edges exceeds the current density at which electromigration occurs. ### Claim 19 (depends on 1) An antenna according to claim 1, said antenna being configured to irradiate radiation in the frequency range from 0.25 GHz to 100 THz. ### Claim 20 (depends on 1) An antenna according to claim 1, further comprising means for measuring the current flowing through the electrodes. ### Claim 21 (depends on 20) An antenna according to claim 20, being configured to detect radiation in the frequency range from 0.25 GHz to 100 THz.