Diamond crystal, diamond devices, magnetic sensor, magnetic sensor system, and method for manufacturing sensor array
A diamond crystal according to the present invention has an NV region containing a complex (NV center) of nitrogen substituted with a carbon atom and a vacancy located adjacent to the nitrogen, on a surface or in the vicinity of the surface, wherein the NV region has a donor concentration equal to or higher than the concentration of the NV centers, or a crystal of the NV region is a {111} face or a face having an off-angle that is ±10 degrees or less against the {111} face, and a principal axis of the NV center is a <111> axis that is perpendicular to the {111} face. Such a diamond crystal enables almost 100% of the NV center to be a state (NV − ) of having a negative electric charge, and spin states of the NV − centers to be aligned in one direction.
1. A diamond device using diamond, comprising a second region formed so as to be in contact with a first region that contains a complex (NV center) of nitrogen (N) substituted with a carbon atom of the diamond and a vacancy (V) located adjacent to the nitrogen, and has a donor concentration higher than that in the first region, wherein
the diamond is a n-type diamond film that is formed on a substrate by a CVD method,
the first regions are two-dimensionally and periodically arrayed in a plane, and the second regions each having the donor concentration higher than that in the first region are formed on respective side faces or peripheries of the first regions, and
a crystal face of the first region is a {111} face or a face having an off-angle that is ±10 degrees or less against the {111} face, and a principal axis of the NV center is a <111> axis that is perpendicular to the {111} face.
2. The diamond device according to claim 1 , wherein the second region is formed of n-type diamond, and the first region is formed of i-type or p-type diamond.
3. The diamond device according to claim 1 , wherein the second region is formed of n-type diamond, and the first region is a depletion region formed by a p-n junction.
4. The diamond device according to claim 1 , wherein the second region has an n+ type of conductivity type of which a donor level is 1×10 18 cm −3 or higher.
5. The diamond device according to claim 1 , wherein a second region that has an NV center concentration lower than that in the first region is formed so as to be in contact with the first region.
6. The diamond device according to claim 1 , wherein the first region has a donor concentration equal to or higher than the concentration of the NV centers in the first region.
7. The diamond device according to claim 1 , wherein the donor concentration is in a range of 10×10 15 cm −3 to 10×10 19 cm −3 .
8. The diamond device according to claim 1 , further comprising an electric field generating unit that has at least two electrodes that are provided so as to face each other, on upper and lower face sides or side face sides of a diamond crystal portion containing the first region.
9. The diamond device according to claim 1 , wherein a periodic array of the first regions is a square periodic array in which the center of the first region is positioned on each lattice point of a two-dimensional square lattice, when the plane is viewed from above.
10. The diamond device according to claim 1 , wherein a periodic array of the first regions is a hexagonal packed array in which on six vertexes of a regular hexagon that has a center point on a center position of a particular first region, the centers of the other first regions are positioned respectively, when the plane is viewed from above.
11. A magnetic sensor comprising:
the diamond device according to claim 1 ; and
an optical sensor that detects an optical signal that is an optical signal emitted from the respective surfaces of the first regions and is generated originating from electron spin resonance in the NV center.
12. A magnetic measurement system provided with the magnetic sensor according to claim 11 , comprising:
a sample stage that is provided so as to face the diamond device; an optical system that irradiates the diamond device with green light;
a microwave generating unit that irradiates the diamond device with a microwave of which a frequency is variable; and
a signal processing unit that processes an optical signal that has been detected by the optical sensor and has been generated originating from electron spin resonance in the NV center.
13. The magnetic measurement system according to claim 12 , further comprising: an electric field generating unit that has at least two electrodes that are provided so as to face each other, on upper and lower face sides or side face sides of a diamond crystal portion containing the first region.
14. The diamond device according to claim 1 , further comprising an electrode for applying a positive potential, which is provided through an insulating film, on one principal surface side of the first region.
15. The diamond device according to claim 1 , wherein the first regions are two-dimensionally and periodically arrayed in a plane, and electrodes for applying a positive potential are provided on respective one principal surface sides of the first region, through an insulating film.