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The n-type doping of diamond is quite difficult, hindering the development of diamond-based electronic devices for decades. In this work, we have designed a boron–nitrogen co-doping technique to realize n-type diamonds. Basically, the activation energy of the donors has been greatly reduced by around 50%, thanks to the successful synthesis of the boron–nitrogen related donor-like complex by a fine control of the synthesis condition. Compared to the sole nitrogen doping scheme, it is found that the co-incorporation of boron elements is beneficial to a lot of aspects, including better crystalline quality, faster growth, higher nitrogen solubility, and stability. With the technique, a p-i-n diamond homojunction has been fabricated. A clear rectification behavior has been recorded, demonstrating that the current co-doping technique we proposed is a feasible path to the accessible n-type diamond.

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 H2/CH4 plasma is proposed to explain the efficient suppression of the incorporated nitrogen. Briefly, adding H2S decreases the growth rate and the resulting (S or S2) 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. [ABSTRACT FROM AUTHOR]