Low resistance light controlled semiconductor switch (lcss)
US20250338640A1
Abstract
A light controlled semiconductor switch (LCSS), method of making, and method of using are provided. In embodiments, a lateral LCSS includes: a semiconductor body including a photoactive layer of gallium nitride (GaN) doped with carbon; a first electrode in contact with a first surface of the semiconductor body; and a second electrode in contact with the first surface of the semiconductor body, the first and second electrodes defining an area through which light energy from at least one light source can impinge on the first surface, wherein the LCSS is configured to switch from a non-conductive off-state to a conductive on-state when the light energy impinging on the semiconductor body is sufficient to raise electrons within the photoactive layer into a conduction band of the photoactive layer.
Description (excerpt)
CROSS-REFERENCE TO RELATED APPLICATIONS This Application is Continuation of U.S. Nonprovisional patent application Ser. No. 18/463,540, filed Sep. 8, 2023, which claims the benefit of U.S. Provisional Patent Application No. 63/405,018 filed Sep. 9, 2022. The Provisional Application, and all references cited herein, are hereby incorporated by reference into the present disclosure in their entirety. FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT The United States Government has ownership rights in this invention. Licensing inquiries may be directed to Office of Technology Transfer, US Naval Research Laboratory, Code 1004, Washington, D.C. 20375, USA; +1.202.767.7230; techtran@nrl.navy.mil, referencing Navy Case No. 211221-US3. BACKGROUND OF THE INVENTION Aspects of the present invention relate generally to semiconductor switches and, more particularly, to light controlled semiconductor switches (LCSS). Light controlled semiconductor switches (LCSS) are opto-electrical devices made of semiconductor material that conduct electricity when they are turned on with light through optical excitation. In general, when photon energy is sufficient to excite electrons into the conduction band of the LCSS semiconductor material, free electrons are generated in the semiconductor conduction band and electrical current flows through the LCSS. LCSSs have been fabricated from silicon (Si), gallium arsenide (GaAs), silicon carbide (SiC), and gallium nitride (GaN) for Radio Frequency (RF) generation applications, for example. Light controlled switches have been fabricated from semi-insulating silicon carbide for power switching application. In one example, a silicon carbide light controlled switch for power switching applications uses vanadium as an extrinsic dopant to make semi-insulating silicon carbide and sub bandgap illumination. The resistance of a light controlled switch for power switch applications is related to the photoresponsivity to photogenerate carriers in the conduction band and the minority carrier lifetime. The photoresponsivity is reduced for silicon carbide because silicon carbide is an indirect bandgap semiconductor and sub bandgap illumination is used. The minority carrier lifetime in vanadium doped silicon carbide is less than 20 nanoseconds (ns) and reduces the density of free electron carriers in the conduction band. The resistance of the vanadium doped silicon carbide light controlled switch is not reported. SUMMARY OF THE INVENTION In a first aspect of the invention, a vertical light controlled semiconductor switch (LCSS) comprises: a semiconductor body including a photoactive layer of gallium nitride (GaN) doped with carbon; a first electrode in contact with a first surface (e.g., top surface) of the semiconductor body, the first electrode defining an area through which light energy from at least one light source can impinge on the first surface; and a second electrode in contact with a second surface (e.g., bottom surface) of the semiconductor body opposed to the first surface, wherein the LCSS is configured to switch from a non-conductive off-state to a conductive on-state when the light energy impinging on the semiconductor body is sufficient to excite electrons into the conduction band of the semiconductor body photoactive layer. In another aspect of the invention, a lateral light controlled semiconductor switch (LCSS) comprises: a semiconductor body including a photoactive layer of gallium nitride (GaN) doped with carbon; a first electrode in contact with a first surface (e.g., top surface) of the semiconductor body; and a second electrode in contact with the first surface of the semiconductor body, the first and second electrodes defining an area through which light energy from at least one light source can impinge on the first surface, wherein the LCSS is configured to switch from a non-conductive off-state to a conductive on-state when the light energy impinging on the semiconductor body is sufficient to excite electrons into the conduction band of the semiconductor body photoactive layer. In embodiments, the semiconductor body includes a substrate selected from the group consisting of direct bandgap GaN, effective direct bandgap gallium oxide (Ga 2 O 3 ), and indirect bandgap silicon carbide (SiC). The term direct bandgap as used herein refers to a material where a top of the valance band and the bottom of the conduction band occur at the same value of momentum. The term effective direct bandgap as used herein means that the semiconductor indirect bandgap is less than 0.25 eV narrower than the semiconductor direct bandgap. Beta gallium oxide has a narrowest bandgap of 4.73 eV with a direct bandgap of 4.78 eV. Alpha gallium oxide has a narrowest bandgap of 5.29 eV and a direct bandgap of 5.52 eV. In implementation, the LCSS has a resistivity less than 850 ohm-millimeters (Ω*mm) and a sheet resistance of less than 3500 ohms per square. The term sheet resistance refers to the resistance of a square piece of a thin material with contacts made to two oppos
Filing details
- Inventors
- Andrew D. Koehler
- Assignee
- The Government Of The United States Of America, As Represented By The Secretary …
- Filed
- Jul 2, 2025
- Granted
- Application pending
Bibliographic data and excerpted text sourced from Google Patents (public record) as part of IP TechMatch's current-filings monitor. This filing is not part of the 2019 historical archive. For the authoritative full text, drawings, and legal status, see the source links above or consult USPTO records directly.