In recent years, the CVD for synthetic diamonds has been constantly improved. Meanwhile, a variety of new deposition methods, with more than 10 different methods, have been developed, each excite the method in different ways. Spitsyn et al
[55] classified the CVD process into four different types, as shown in
Fig. 9. According to thermal, chemical, electrical and electromagnetic techniques to further decompose and excite the gas, the most common ones are MPCVD, HF CVD, and DC arc jet CVD, among them, HF CVD is the most widely used methods because of their simple equipment, stable and easy to control conditions, hence they exhibit great potential for the artificial synthesis of diamond films (microdiamond, nanodiamond, and ultra-nanodiamond).
