The core issue for the implementation of NV center qubit technology is a sensitive readout of the NV spin state. We present here a detailed theoretical and experimental study of NV center photoionization processes, used as a basis for the design of a dual-beam photoelectric method for the detection of NV magnetic resonances (PDMR). This scheme, based on NV one-photon ionization, is significantly more efficient than the previously reported single-beam excitation scheme. We demonstrate this technique on small ensembles of ∼10 shallow NVs implanted in electronic grade diamond (a relevant material for quantum technology), on which we achieve a cw magnetic resonance contrast of 9%-three times enhanced compared to previous work. The dual-beam PDMR scheme allows independent control of the photoionization rate and spin magnetic resonance contrast. Under a similar excitation, we obtain a significantly higher photocurrent, and thus an improved signal-to-noise ratio, compared to single-beam PDMR. Finally, this scheme is predicted to enhance magnetic resonance contrast in the case of samples with a high proportion of substitutional nitrogen defects, and could therefore enable the photoelectric readout of single NV spins. The negatively charged nitrogen-vacancy (NV -) center in diamond has attracted particular attention as a room temperature solid-state qubit [1] that can be read out by optical detection of magnetic resonances (ODMR) [2]. Numerous applications in the field of solid-state quantum information processing [3] and sensing [4][5][6][7][8][9][10] are being studied.We have recently developed a method for the photoelectric detection of NV -electron spin magnetic resonances (PDMR) [11], performed directly on a diamond chip equipped with electric contacts and based on the electric detection of charge carriers promoted to the diamond conduction band (CB) by two-photon ionization of NV -under green illumination (single-beam PDMR, or s-PDMR) (Fig. 1) To explore the photophysics behind the PDMR scheme and optimize its performances, we performed ab initio calculations of N 0 s , NV -, and NV 0 ionization cross sections, and compared the results to experimental characterizations of the ionization bands. In this way we demonstrate that under blue illumination, the ionization of NV -can be achieved by a more effective one-photon process, leading to a higher photocurrent-and therefore a higher signal-to-noise (S/N) ratio-than green illumination of identical power. Based on this result, we designed a dual-beam PDMR (d-PDMR) scheme (Fig. 1), in which pulsed blue light directly ionizes NV -and converts the resultant NV 0 back to NV -by one-photon processes, while simultaneous cw green illumination independently controls the MR contrast. We validated this scheme on small ensembles of ∼10 shallow NV -centers implanted in electronic grade diamond, which represents a downscaling of the photoelectric detection by a factor ∼10 5 compared to a previous publication [11]. The d-PDMR scheme leads to enhanced MR contrast under low power illu...

The fabrication of n-type diamond is essential for the realization of electronic components for extreme environments. We report on the growth of a 66 μm thick homoepitaxial phosphorus-doped diamond on a (110)-oriented diamond substrate, grown at a very high deposition rate of 33 μm h−1. A pristine diamond lattice is observed by high resolution transmission electron microscopy, which indicates the growth of high quality diamond. About 2.9 × 1016 cm−3 phosphorus atoms are electrically active as substitutional donors, which is 60% of all incorporated dopant atoms. These results indicate that P-doped (110)-oriented diamond films deposited at high growth rates are promising candidates for future use in high-power electronic applications.