A method utilising microwave plasma chemical vapour deposition (MPCVD) process of producing electronic device grade single crystal diamond comprising of: (a) selecting a diamond seed or substrate having a pre-determined orientation, (b) cleaning and/or etching of non-diamond phases and other induced surface damages from the diamond seed or substrate, whereby this step can be performed one or more times, (c) growing a layer of extremely low crystal defect density diamond surface on the cleaned/etched diamond seed or substrate, whereby this step can be performed one or more times, and (d) growing electronics device grade single crystal diamond on top of the layer of the low crystal defect density diamond surface.