Boron Incorporation Efficiency in Diamond: Influence of Gas Composition, Crystal Orientation, and Substrate Temperature

In this work, boron incorporation in diamond grown by microwave plasma-enhanced chemical vapor deposition is investigated as a function of methane concentration, boron precursor concentration, crystalline orientation, oxygen addition to the plasma, and deposition temperature. The boron incorporation efficiency, i.e., the ratio between the boron concentration in diamond and the gas-phase boron-to-carbon ratio, spans several orders of magnitude and can exceed unity for all investigated crystalline orientations. Overall results demonstrate that methane concentration and the substrate’s crystalline orientation are key factors governing boron incorporation. The temperature study reveals that boron incorporation is also governed by thermally activated boron-loss mechanisms. Finally, all results show that boron incorporation is not exclusively controlled by the plasma composition but also by surface growth mechanisms.