SOLID STATE ELECTRIC FIELD SENSOR

This disclosure relates to an electrical field sensor. The sensor comprises a diamond substrate with a conducting surface providing positive charge carriers and multiple defects disposed in the diamond substrate. The sensor further comprises an optical apparatus to initialise and readout the multiple defect vacancies to determine the electrical field based on a detected fluorescence of the multiple defects. The multiple defects are located at a depth below the surface to enable the positive charge carriers to reach and positively charge the multiple defect vacancies under an influence of an external negative electric field to thereby alter the fluorescence of at least some of the multiple defects. Since the fluorescence can be measured optically, no electrical connections or amplifiers are required on the surface, which means significantly higher densities of sensors can be implemented.