Transient coexistence of excitons and charge carriers in high-purity diamond

Abstract We investigate the transient coexistence state of the excitons and charge carriers in highly-pure diamond after an impulsive injection of excitons, by probing free electrons until the relaxation of carriers with the nanosecond time-resolved cyclotron resonance (TRCR) method. By analyzing the time profiles of the TRCR signal with a numerical solution of rate equations for exciton and charge carrier densities over a wide temperature range from 10 K to 261 K, the temperature dependence of the coefficient of two-body (Auger) collision of excitons, the rate of thermal dissociation of excitons, and exciton and electron lifetimes was extracted. The shift of exciton dissociation mechanisms from the Auger process below 40 K to the thermal ionization above 80 K was revealed for an initial density of excitons in the order of 1015 cm−3. We also found that the equilibrium between electrons and excitons is established within 100 ns above 80 K, when the thermal ionization of excitons dominates the dissociation process. These results provide fundamental understandings of transient carrier correlation in optoelectronic devices.