In this work, sulfur addition has been employed on the boron-doped diamond growth process, and a significant regulation of the boron doping and the growth behavior has been realized by microwave plasma chemical vapor deposition. It is interesting to find that the sulfur incorporation will lead to an accordant evolution on the boron doping efficiency, hole mobility and concentration, crystal quality, surface morphology, and growth rate. In the presence of sulfur with appropriate dosage, for a boron-to-carbon ratio of only 2.5 ppm in gas phase during growth, a very high doping concentration of 1.2 × 1019 at/cm3 has been achieved, indicative of a very efficient boron doping. Besides, the hole mobility of the sample is 853 cm2/V s at 300 K, which is better than the state of the art for p-type doping in diamond. The regulation mechanism of the sulfur addition will be discussed from the point of view of sulfur-induced plasma change and possible B–S complex formation. This study may provide an effective way for high-quality p-type conductive diamond layer growth and further for the potential diamond-based opto-electronic device applications.

Size dependence of glutathione capped CdTe quantum dots (GSH-CdTe QDs) on the sensitivity and selectivity in the fluorometric detection of ferrous (II) ions (Fe2+) has been systematically investigated. Smaller-size QDs show higher sensitivity in the detection of Fe2+, resulting in higher quenching efficiency and red shift of the fluorescence peak of QDs. Stern–Volmer plots indicate that the charge transfer model can be employed to account for the observed fluorescence quenching effect. Fe2+ is bound to the surface of QDs by GSH and excited electrons are transferred from QDs to Fe2+, which facilitates a nonradiative recombination process and a decrease in the PL efficiency. In addition, the results from time resolved photoluminescence and a confocal scanning fluorescence microscope have shown that smaller-size QDs have a faster decrease in the fluorescence lifetime compared with that of larger-size QDs with Fe2+ addition, suggesting that the fast charge transfer in smaller-size QDs should be responsible for the observed fluorescence quenching effect. This Letter provides a comprehensive understanding of the mechanism of the fluorescence for the CdTe QDs quenched by Fe2+.

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In this work, a sulfur and nitrogen co-doping technique has been demonstrated for diamond epilayer growth by microwave plasma chemical vapor deposition (MPCVD). Results show that the nitrogen concentration in films could be tailored by co-doping of sulfur. At a certain growth condition, single nitrogen-vacancy (NV) colour centers could be achieved. A competition mechanism between sulfur and nitrogen incorporation in the H 2 /CH 4 plasma is proposed to explain the efficient suppression of the incorporated nitrogen. Briefly, adding H 2 S decreases the growth rate and the resulting (S or S 2 ) species could react with the dissociated nitrogen atoms to form S and N-containing clusters. Hence, the concentration of the NV centers in diamond is decreased. Meanwhile, density functional theory (DFT) calculations indicate an increment of the NV formation energy in the presence of sulfur, which confirms that sulfur has a suppression effect on the formation of the NV centers. This study provides a new method to adjust the concentration of the NV centers in the diamond films.