Comparative study of excitonic recombination radiation from diamonds grown by CVD and HP/HT methods

Abstract

Abstract Intensive and dominant free-exciton (FE) recombination radiation is observed from chamber flame (CF) diamonds, and high pressure and high temperature (HP/HT) diamonds. The FE recombination radiation associated with one TO phonon (FETO) intensity from CF and HP/HT diamonds increases as temperature decreases from room temperature until 120 and 110 K, respectively, and saturates below these temperatures which are 30–50 K lower than the temperature at which the FETO intensity from microwave plasma chemical vapor deposition (MPCVD) diamond saturates. The crystallinity of CF, HP/HT and MPCVD diamonds is discussed by the saturation temperature depending on the non-radiative transition probability caused by intrinsic dissociation of FE. Increase of the FETO intensity is observed from an oxygen-terminated surface. The FETO intensity from oxygen-terminated surface of CF isolated particle is about three times larger than that from hydrogen-terminated surface. The change of the FETO intensity is explained by the difference in the surface electronic structure and/or the surface band bending between the oxygen- and hydrogen-terminated surfaces.