# US 7,465,595 B2 · Quantum device, manufacturing method of the same and controlling method of the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,465,595 B2 - Document ID: US7465595B2 - Status: Granted - Kind: B2 - Application number: 11/064,497 - Filed: 2005-02-24 - Published: 2006-05-11 - Granted: 2008-12-16 - Earliest claimed: 2004-11-09 - Assignees: Fujitsu Limited - Inventors: Haizhi Song; Tatsuya Usuki - Web page: https://patentgrep.com/patent/US7465595B2 ## CPC - H10D 48/383: {Quantum effect devices, e.g. of devices using quantum reflection, diffraction or interference effects} - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - H10D 48/3835: {Semiconductor qubit devices comprising a plurality of quantum mechanically interacting semiconductor quantum dots, e.g. Loss-DiVincenzo spin qubits} - H10D 62/814: {Quantum box structures} - G01Q 80/00: Applications, other than SPM, of scanning-probe techniques (manufacture or treatment of nanostructures B82B3/00; recording or reproducing information using near-field interaction G11B9/12, G11B11/24, G11B13/08) - Y10S 438/962: Quantum dots and lines - Y10S 977/938: Field effect transistors, FETS, with nanowire- or nanotube-channel region - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - G01Q: SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM] - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract By bringing a tip of an AFM into contact with the surface of a GaAs substrate or an AlGaAs substrate, for example, applying a negative bias to the tip, and applying a positive bias to the GaAs substrate or the AlGaAs substrate, a donut-shaped oxide film is formed. Then, the oxide film is removed. As a result, a ring-shaped groove is formed in the surface of the GaAs substrate or the AlGaAs substrate. The oxide film can be removed by chemical etching, ultrasonic cleaning with water, a treatment with atomic hydrogen in a vacuum, or the like. Thereafter, a semiconductor film (InAs film or InGaAs film, for example) is epitaxially grown in the groove. Then, a capping layer which covers the semiconductor film and the GaAs substrate or the AlGaAs substrate is formed. ## Claims ### Claim 1 A manufacturing method of a quantum device, comprising the steps of: bringing a tip of an atomic force microscope to which a negative bias is applied into contact with a surface of a semiconductor substrate to form a ring-shaped oxide film on the surface of the semiconductor substrate in an atmosphere containing water; forming a ring-shaped groove in the surface of the semiconductor substrate by removing the oxide film; and growing a semiconductor film in the groove. ### Claim 2 (depends on 1) The manufacturing method of the quantum device according to claim 1, wherein in said step of forming the oxide film, a portion of the semiconductor substrate which the tip touches is protected from oxidation. ### Claim 3 (depends on 1) The manufacturing method of the quantum device according to claim 1, wherein the semiconductor film is epitaxially grown. ### Claim 4 (depends on 1) The manufacturing method of the quantum device according to claim 1, wherein said step of removing the oxide film comprises the step of subjecting the oxide film to chemical etching. ### Claim 5 (depends on 1) The manufacturing method of the quantum device according to claim 1, wherein said step of removing the oxide film comprises the step of subjecting the oxide film to ultrasonic cleaning with water. ### Claim 6 (depends on 1) The manufacturing method of the quantum device according to claim 1, wherein said step of removing the oxide film comprises the step of subjecting the oxide film to a treatment with atomic hydrogen in a vacuum. ### Claim 7 (depends on 1) The manufacturing method of the quantum device according to claim 1, further comprising the step of depositing a single impurity atom on the surface of the semiconductor substrate before said step of forming the oxide film, the oxide film being formed so that the impurity atom is located at a center thereof. ### Claim 8 (depends on 1) The manufacturing method of the quantum device according to claim 1, further comprising the step of depositing a single impurity atom on a center of the oxide film between said step of forming the oxide film and said step of removing the oxide film. ### Claim 9 (depends on 7) The manufacturing method of the quantum device according to claim 7, further comprising the step of diffusing the impurity atom into the semiconductor substrate by a thermal treatment after said step of depositing the impurity atom. ### Claim 10 (depends on 7) The manufacturing method of the quantum device according to claim 7, wherein one selected from the group consisting of Si, Be, Fe and Co is deposited as the impurity atom. ### Claim 11 (depends on 1) The manufacturing method of the quantum device according to claim 1, further comprising the steps of: introducing impurity atoms into the surface of the semiconductor substrate before said step of forming the oxide film; and oxidizing a portion around the oxide film between said step of forming the oxide film and said step of removing the oxide film, in said step of forming the oxide film, the oxide film being formed so that one of the impurity atoms is located in a center thereof, and in said step of removing the oxide film, the oxide film and the oxidized portion therearound being removed. ### Claim 12 A manufacturing method of a quantum device, comprising the steps of: introducing impurity atoms into a surface of a semiconductor substrate; bringing a tip of an atomic force microscope to which a negative bias is applied into contact with the surface of the semiconductor substrate to form a ring-shaped oxide film and a plurality of dot-shaped oxide films on the surface of the semiconductor substrate in an atmosphere containing water; oxidizing portions around the ring-shaped oxide film and the dot-shaped oxide films; forming a ring-shaped groove and dot-shaped pits in the surface of the semiconductor substrate by removing the ring-shaped oxide film and the dot-shaped oxide films and removing the oxidized portions therearound; and growing semiconductor films in the groove and the pits. ### Claim 13 (depends on 1) The manufacturing method of the quantum device according to claim 1, wherein a diameter of the ring-shaped oxide is 50 nm or less. ### Claim 14 (depends on 13) The manufacturing method of the quantum device according to claim 13, wherein a diameter of the ring-shaped oxide film is 20 nm or less. ### Claim 15 (depends on 1) The manufacturing method of the quantum device according to claim 1, wherein as the tip, a tip made of a carbon nano-tube is used, and a diameter of the ring-shaped oxide film is 10 nm or less. ### Claim 16 (depends on 1) The manufacturing method of the quantum device according to claim 1, wherein as the semiconductor substrate and the semiconductor film, those made of a compound semiconductor are used, respectively. ### Claim 17 A controlling method of a quantum device comprising a qubit which includes a quantum ring, a single nuclear spin surrounded by the quantum ring, and a quantum dot adjacent to the quantum ring, said controlling method comprising: moving an electron which exists in the quantum ring into the quantum dot by applying an optical pulse to the qubit to cause optical excitation. ### Claim 18 (depends on 17) The controlling method of the quantum device according to claim 17, wherein the qubit contains SiGe. ### Claim 19 (depends on 17) The controlling method of the quantum device according to claim 17, wherein the nuclear spin is that of a 31P atom. ### Claim 20 (depends on 17) The controlling method of the quantum device according to claim 17, further comprising: returning the electron in the quantum dot into the quantum ring by applying an optical pulse to the qubit to cause optical excitation; and making hyperfine interaction function between a spin of the electron in the quantum ring and the nuclear spin to rotate the nuclear spin. ### Claim 21 (depends on 20) The controlling method of the quantum device according to claim 20, wherein said step of rotating the nuclear spin comprises the step of applying a pulse with a resonant frequency to the qubit. ### Claim 22 (depends on 17) The controlling method of the quantum device according to claim 17, wherein the quantum device comprises a plurality of the qubits, and respective quantum rings of the plurality of qubits are placed side by side on one line, said controlling method further comprising, for the adjacent two out of the plurality of qubits, the steps of: returning electrons in the quantum dots into the quantum rings; and making exchange interaction function between spins of two electrons in the quantum rings to rotate the nuclear spins. ### Claim 23 (depends on 22) The controlling method of the quantum device according to claim 22, wherein said step of rotating the nuclear spins comprises the step of applying a magnetic field to the two qubits. ### Claim 24 A manufacturing method of a quantum device, comprising the steps of: bringing a tip of an atomic force microscope to which a negative bias is applied into contact with a surface of a semiconductor substrate to form a ring-shaped oxide film and a dot-shaped oxide film adjacent to each other on the surface of the semiconductor substrate in an atmosphere containing water; depositing a single impurity atom on a center of the ring-shaped oxide film; forming a ring-shaped groove and a dot-shaped pit in the surface of the semiconductor substrate by removing the ring-shaped oxide film and the dot-shaped oxide film; and forming a quantum ring and a quantum dot by growing semiconductor films in the groove and the dot. ### Claim 25 A manufacturing method of a quantum device, comprising the steps of: introducing impurity atoms into a surface of a semiconductor substrate; bringing a tip of an atomic force microscope to which a negative bias is applied into contact with the surface of the semiconductor substrate to form a ring-shaped oxide film and a dot-shaped oxide film adjacent to each other on the surface of the semiconductor substrate in an atmosphere containing water; oxidizing portions around the ring-shaped oxide film and the dot-shaped oxide film; forming a ring-shaped groove and a dot-shaped pit in the surface of the semiconductor substrate by removing the ring-shaped oxide film and the dot-shaped oxide film and removing the oxidized portions therearound; and forming a quantum ring and a quantum dot by growing semiconductor films in the groove and the pit. ### Claim 26 (depends on 24) The manufacturing method of the quantum device according to claim 24, wherein a plurality of qubits each comprising the quantum ring and the quantum dot are formed simultaneously so that the quantum rings are adjacent to each other. ### Claim 27 (depends on 25) The manufacturing method of the quantum device according to claim 25, wherein a plurality of qubits each comprising the quantum ring and the quantum dot are formed simultaneously so that the quantum rings are adjacent to each other.