Investigation of boron-doped delta layers in CVD diamond grown on single-sector HPHT substrates

This work is devoted to experimental study of boron doped delta layers in CVD diamond. Delta layers with a thickness of 0.8 – 2 nm were grown with a concentration of boron atoms of (1 – 1.7) $\cdot$ 10$^{21}$ cm$^{-3}$, and localized inside undoped defect-free diamond. The layers thickness and boron concentration were measured by secondary ion mass spectrometry (SIMS). The surface density and the Hall mobility of holes, the layer resistance at room temperature, and temperature dependences of these parameters are presented. Performed electrical measurements showed that, despite the perfect (from the point of view of the possibility of quantum effects) profile of delta layers, no significant increase was observed in the hole mobility compared to uniform doping with the same concentration of boron atoms. An explanation is proposed for the results of electrical measurements based on calculations of the delta layer profile and the concentration of delocalized holes depending on the layer thickness. It is discussed which parameters of the boron doped delta layers are needed in order to obtain a significant increase of the hole mobility in heavily doped diamond.