Exciton condensation in homoepitaxial chemical vapor deposition diamond

In this work, the characteristics of the edge emission of a homoepitaxial diamond sample grown by chemical vapor deposition (CVD) are reported. Photoluminescence has been excited at 220 nm by using a tunable optical parametric oscillator laser, giving ~5 ns wide laser pulses. The temperature of the sample has been decreased from room temperature down to 30 K. Free exciton emission and its phonon replicas have been observed at all the temperatures explored. Excitonic lifetime shows a nonmonotonic dependence on the sample temperature. Luminescence at low temperatures from electron-hole drops at approximately 5.18 eV has been observed for the first time in CVD diamond.