Farbzentren im Kristall : NV(Stickstoff-Fehlstellen)-Zentren in hochreinen Diamant-Einkristallen
Mit der Frage nach Kristallgitterverunreinigungen im Diamanten beschäftigt sich dieser Text. Diese sogenannten NV-Zentren haben ein enormes Potenzial für Anwendungen wie Biosensoren für die Medizintechnik oder Quantencomputer.
Photons from ideal single-photon sources exhibit quantum mechanical characteristics and are therefore suited to applications in novel fields, including quantum cryptography and spintronics. However, the biggest challenge for the implementation of this concept is maintaining the coherence of the quantum states for a sufficiently long time. One promising candidate for this task is the nitrogen-vacancy center in diamond. The N-V center is a point defect in diamond and one of its properties is strong photoluminescence, which can be detected spectroscopically. The electron spins at N-V centers can be manipulated at room temperature by applying magnetic or electric fields, microwave radiation or light, or a combination of these, resulting in sharp resonances in the intensity and wavelength of the photoluminescence. An individual N-V center can thus be viewed as a very sensitive sensor for these effects. The main aim of this project is the fabrication and investigation of near-surface N-V centers in highpurity single-crystal diamond films. Preparation of these active elements close to the surface with good properties is a task which has not yet been sufficiently accomplished, especially when read-out is desired to be performed using both optical and electronical means. In this project the influence of diamond properties, as well as the structure and termination of the diamond surface at the spin centers, is investigated. Pure single-crystal diamond films are homoepitaxially grown by microwave plasma-assisted chemical vapor deposition and the film quality is characterized by standard methods. N-V centers are produced by ion implantation and properties of these are spectroscopically investigated.