Plasma Antennas Limited

Ruth Elizabeth Harper

David Hayes

Richard Brooke Keeton

A solid state plasma monolithic microwave integrated circuit having single or multiple elemental devices with at least three terminals operating within the microwave, millimeter wave or terahertz bands, that can be configured within a parallel plate structure, which solid state plasma monolithic microwave integrated circuit comprises: (i) a semiconductor dielectric substrate (); (ii) parallel plates () which comprise an upper conducting parallel plate () and a lower conducting parallel plate () and which parallel plates () are used to guide an electromagnetic wave; (iii) an isolating trench which is between the parallel plates (), and which is used to contain a solid state plasma; (iv) a distinct p-doped region and a distinct n-doped region which are within a first semiconductor region defined by the isolating trench below the upper conducting parallel plate (), and which are connected to two electrical bias terminals, where at least one electrical bias terminal forms a radio frequency short to the upper parallel plate (); and a p or n doped region within a second semiconductor region defined by the isolating trench above the lower conducting parallel plate () and connected to a third electrical bias terminal, where the third electrical bias terminal forms a radio frequency short to the lower conducting parallel plate (), and wherein; a solid state plasma is able to be controlled by voltage biasing of the three electrical bias terminals to either reflect, absorb or transmit an electromagnetic wave.

Three terminal solid state plasma monolithic microwave integrated circuit

A solid state electronically steerable antenna can be generated from a sheet of semiconductor material by forming a pattern of localised plasma regions in the sheet, either by injecting carriers into, or by generating carriers in, those localised regions. A suitable solid state plasma antenna can be made from a silicon wafer () by first thermally oxidising the surfaces and subjecting the wafer () to a high temperature stabilisation process to improve the stoichiometry at the silicon/silica interface, and optionally also performing a low-temperature bake in a gas mixture including hydrogen. This produces a wafer () with a long minority carrier lifetime. Regions of the wafer () in which plasma may be generated are then defined by reticulation to form isolated regions with high minority carrier lifetime. The resulting discrete regions may be of a size less than 1 mm, for example 0.3 mm.

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Didcot, United Kingdom

Ruth Elizabeth Harper