Hall effect analysis of boron and nitrogen background concentration in undoped CVD diamond

Pure single crystal diamond is a superior material for electronic, quantum, and detection applications. The state-of-the-art level of background concentrations of boron and nitrogen in such diamonds is about 1 ppb, which is quite close to the detection limit of the best chemical analysis techniques. In this work, we show that the boron concentration of ∼0.1 ppb causes conductivity of ∼5 kΩ cm of the single crystal diamond if the nitrogen concentration is lower. In such a case, the temperature dependent Hall effect measurement provides ∼100 times better detection limit for the concentration of the impurities in diamond compared to the conventional optical techniques. As a result, we have found the background concentrations of boron and nitrogen at the level of 0.07 and 0.02 ppb, respectively. This fact leads to a conclusion that growth of the insulating diamond is possible only when the nitrogen concentration is higher than the boron concentration.