Peculiarities of SHB in the 637 nm line of N–V defects in CVD-grown diamond films

Abstract

Strain field inside nitrogen-doped CVD diamond film has been investigated by using the luminescence and excitation spectra of 637-nm zero-phonon line (ZPL) of N–V centres. At 2 K the ZPL measured in the excitation spectrum had a Lorentzian shape, while the ZPL measured in luminescence spectrum had an asymmetry in shape and was shifted to the red side as compared to the excitation spectrum. The differences vanish with the increase of temperature up to ∼50 K. SHB was performed by using a single-frequency dye laser. It revealed a dependence of the holewidth on the position of the burning frequency inside the ZPL. A model which takes into account a random strain-induced splitting of the excited 3E states in ensemble of N–V defects in a polycrystalline film was used to explain the peculiarities observed in the luminescence and SHB spectra.